=128.= _Tin solders._ I. (ordinary soft solder.) Tin, 2 parts; lead, 1

part.

II. (Harder, and known as “Plumbers’ Sealed” solder.) Tin, 1 part;

lead, 2 parts.

III. Many other proportions of tin and lead are occasionally used,

ranging from tin, 1 part; lead, 25 parts, to tin, 6 parts; lead, 1 part.

IV. (Very fusible solder, melting in boiling water.) Lead, 3 parts;

tin, 5 parts; bismuth, 8 parts. The fusibility is still further

increased by adding mercury or cadmium.

=129.= _Spelter solders._ (Used for brazing.) Copper and zinc in

varying proportions. It becomes more fusible as the amount of zinc

present is increased.

METHODS OF SOLDERING.

=130.= A thorough cleansing of the surfaces to be united is always

needful, but more especially so in the case of soft soldering. It may

be effected by means of acids, or with a graver or scraper, etc.;

the cleansed surfaces must not be touched with the fingers, and the

soldering should be done at once. If acids are employed, the objects

should be thoroughly washed after soldering, in order to avoid rust;

and, after drying, they should be rinsed with alcohol.

The parts to be soldered are held in position with clamps, tweezers,

pins, or iron wire. This latter, known as _binding wire_, is used for

delicate objects and should be very pliable. When a high degree of heat

is to be applied, all risk of the iron uniting with gold may be avoided

by mixing a little sandiver with the borax employed. (See article

=153=).

Before heating, if there are already parts united with solder, they

should be covered with borax to prevent softening.

Only a moderate heat should at first be applied, so as to melt the

borax, or sal-ammoniac without displacing it. The violent frothing up,

which is very liable to displace the parts or the fragments of solder,

can thus in a great part be avoided. If a naked lamp-flame is used,

or if it is directed on to the object with a blow-pipe, it should

be, so to speak, large and soft, and the jet should not be directed

to the point of juncture until the solder is observed to have fused.

In soldering brass to steel, it is sometimes necessary to direct the

flame against the brass only, in order, as far as possible, to avoid

softening the steel. The hard solders for gold, silver, etc., require

a considerable degree of heat, so that the objects must be heated to

redness.

=131.= =To solder gold and platinum= to each other or to themselves.

On a hard wetted surface, marble, for example, rub a piece of borax

until a white liquid paste is obtained (or the powdered borax sold by

chemists can be made into paste direct). Having prepared the borax, the

surfaces to be united are cleansed either by scraping or with dilute

nitric acid (=155=); the acid may be previously heated to boiling,

as it will then act more rapidly; and the surfaces are subsequently

scraped. They are now covered with the borax with a paint brush, set in

position, and small pieces of solder placed on the junction. As already

observed, the heating must at first be gentle to avoid displacing the

solder by the frothing of the borax.

=132.= =To solder silver.= Also for uniting gold to silver, or silver,

brass, steel to each other or to themselves. Proceed in the manner

already explained for gold and platinum, except that the borax paste

must be sensibly thicker.

=133.= =To solder tin.= Also for uniting gold, silver, brass to each

other, or to other metals, such as steel, iron, etc. Clean the surface

with a graver or scraper; sulphuric or hydrochloric acid may be used,

but in this case the cleansing afterwards must not be forgotten.

The heating is effected as in soldering gold, unless a soldering iron

is used, when the directions subsequently given should be followed.

=134.= =To solder aluminium.= M. Mourey recommends the following method.

One of the series of aluminium solders, No. II. (art. =125=), is

employed and, as a flux, two-thirds of balsam of copaiba, one-third

very pure Venice turpentine, and a few drops of the juice of a citron;

these constituents are pounded together in order to secure a perfect

admixture.

The surfaces to be united are covered with solder (employing a

soldering iron of aluminium) just as in the case of tinning (=137=),

the flux just mentioned being used. The two surfaces, thus prepared,

are placed in contact and maintained in the required position, and,

after laying on the joint particles of solder that are richer in

aluminium than the one used for preparing the surfaces, the whole is

placed over a charcoal fire or heated before the blow-pipe, pressing

gently on the pieces of solder, which will soon melt and should be

distributed by means of a little tool of aluminium.

During this second stage of the process, it is necessary to be very

cautious in the application of the flux; the pieces of solder should

only be dipped in it before being placed in position, for the flux is

mainly for use in preparing the surfaces; as soon as the solder has run

well, the temperature should be lowered in order not to dry up and burn

the solder, which would be apt to become brittle.

In preparing the solders, the aluminium is first fused and stirred with

a small iron rod; then add the zinc and stir again; add a little tallow

and cast the solder into rods.

The zinc must not be too much heated, as it will volatilize, leaving

the alloy rich in aluminium and therefore brittle.

=135.= =Fluxes for soldering.= Various substances can be employed as

fluxes for cleansing the surfaces to be united:

_Sal-ammoniac_ reduced to powder and made into a paste with sweet

oil, or merely dissolved in water. A paste formed of _sal-ammoniac_

and _resin_, reduced to powder, with water or oil. _Resin_ alone will

suffice for the soft soldering of copper or brass. _Venice turpentine_,

which has the advantage of not causing steel to rust, although it

makes the objects sticky so that they require to be afterwards rinsed

in alcohol or turpentine.

Various acid solutions are sold for the purpose and experience will

enable the watchmaker to select that which is best adapted to his

requirements.

Lastly, saturated _chloride of zinc_ can be recommended. It is prepared

as follows:

Some dilute hydrochloric acid (which also goes by the name of spirits

of salts, or muriatic acid) is placed in a glass flask and strips of

zinc are added one by one; the flask must be left uncorked and the zinc

added a little at a time, lest the effervescence that occurs should

break the vessel. When the zinc added is not acted on by the fluid

it may be concluded that the acid is saturated or “killed,” and the

fluid may then be transferred to a stoppered or corked bottle for use.

In using it, a small quantity is spread over the surfaces that are

to be united and the solder will be found to run with great freedom.

Some authorities recommend the addition of sal-ammoniac to the extent

of one-fourth the weight of acid taken. It is well again to warn the

reader that the pieces must be thoroughly washed after employing these

liquids, for, otherwise, they will cause tools with which they are

brought in contact to rust and will rust themselves if they consist

wholly or in part of iron or steel. The vessel containing the fluid

must be kept well away from the work-bench.

The liquid can be used immediately after being prepared as above

explained; but all acid reaction may be prevented by evaporating at

a moderate temperature until of the consistency of oil; it is then

allowed to cool and kept in a bottle.

=136.= =The soldering iron= with a head of copper, such as is used

by tin-plate workers, is well known; if made on a small scale it

may occasionally be of service to the watchmaker. The tool may be

=T=-shaped, one end of the horizontal portion, the copper head,

terminating in a rather thin blade, and the other enlarged, so that,

when held in the flame of a lamp, it will store up a sufficient amount

of heat. The upright part of the =T= corresponds, of course, to the

handle. After the iron has been heated just short of redness in the

dark, the end of the blade is moistened with soldering fluid and a

small piece of solder attached to it. The object to be united is gently

heated and also moistened with the fluid; the iron charged with solder

is presented to it, often with the enlarged extremity of the head

maintained in the flame of a lamp, and the solder will, as a rule, run

without again heating the object, although this might be done while the

iron is still in contact. It may be found convenient to fix the iron in

a suitable position with the lamp below the large end of the head; the

object will then be brought against the iron after being moistened with

the fluid.

=137.= It is often advisable to tin the surfaces to be united previous

to soldering them; in order to do this they are moistened with

soldering fluid, small pieces of solder are then spread over, and these

are fused by passing the hot iron over the surface; or the solder can

be spread after fusion by means of a metallic rod charged with the

liquid.

=138.= =Brazing.= This operation consists in soldering iron, steel,

brass, or copper, with an easily fusible brass, which is specially

prepared in the form of coarse dust, termed spelter solder, or cut

in thin strips of convenient shape (=129=). The method resembles, in

all essential particulars, the application of hard solders previously

referred to (=131=, etc.)

Heat is usually applied direct by the blow-pipe, borax being used as a

flux, and the precautions taken that are mentioned in article =130=:

it is necessary to avoid a greater degree of heat than would melt the

brass, since the object might in that case be fused. For fine work, it

is better to employ silver solder.

On an emergency, two pieces of steel can be united by brazing and

subsequently hardened, and we have successfully practiced this method

in such a case as the following: A small portion having been broken off

from the quarter-piece of a repeater, we dovetailed into it another

piece of steel of the required form, but a trifle too large at the

upper side. When the brass had run well into the joint, and the piece

was still at a full cherry-red heat, it was hardened, and afterwards

cleaned and tempered to a blue color. The upper surface was then

brought to shape with a good file, resting it on a wooden block against

a projection, and, after making sure that it would act correctly, the

whole was smoothed and polished. It has since worked well and does not

show signs of wear.

BRONZING.

=139.= =To bronze copper.= The following are two methods recommended

for bronzing objects of this metal, for example, a medal.

Dissolve two parts of verdigris (acetate of copper) and one part

of sal-ammoniac in vinegar. Boil the solution, skim it, and dilute

with water until it no longer possesses a feebly metallic smell, nor

produces a whitish precipitate on the addition of water. Then let it

boil again in an earthenware or porcelain vessel and transfer it, while

boiling, into another vessel containing the perfectly clean medals,

etc., and place the whole on the fire. As soon as the medals assume

the required color, remove them, and wash carefully in clean water.

The objects must not be left too long in the acid bath over the fire,

because the layer of oxide would become too thick, and would easily

scale off the surface; whereas, if the operation is properly conducted,

the coating adheres so firmly that it cannot be separated even by

scraping. Of course, it is only after a certain number of trials, and

with experience, that the exact moment can be ascertained for removing

the objects from the bath. It is very necessary that the bath be not

too concentrated, as the superficial oxide becomes proportionately less

adherent: moreover, a whitish powder is deposited on the medal, which

turns green on exposure to the air and spoils the appearance of the

bronzing.

=140.= =Chinese bronzing.= The Chinese employ the following mixture for

bronzing copper, the several constituents being powdered before being

incorporated together: 2 parts of verdigris, 2 parts of cinnabar, 5 of

sal-ammoniac, 5 of alum, and 2 parts of the beak and of the liver of

a duck. A paste having been made, with vinegar, it is spread over the

perfectly clean surface of the copper, and the whole exposed for an

instant to the fire, then allowed to cool, washed, and the operation

repeated as often as may be needed in order to obtain the desired tint.

By adding sulphate of copper to the mixture a browner shade will be

obtained, and it may be made yellower by adding borax. Copper thus

treated is said to present a beautiful appearance, and to be so

permanent that neither air nor water has any influence against it.

=141.= =To bronze brass.= Dissolve copper turnings in nitric acid until

it is completely saturated. Immerse the brass objects to be bronzed in

this solution after they have been cleaned, smoothed with water of Ayr

stone, and heated to such a temperature as the hand can just support;

on being placed over a charcoal fire they will assume a green color;

rub them over with rags, repeat the immersion and heating over charcoal

until the required tint is obtained. The shade may be improved by

oiling the finished surfaces.

It is asserted that by immersing copper articles in molten sulphur

containing lampblack in suspension, they assume the appearance of

bronze; and that they may even be polished without losing their color.

GILDING.

=142.= =Gold gilding without the aid of mercury.= Prepare the gold in

fine powder, as explained in the following paragraph, or procure it

from the dealers in chemical products, who manufacture it of various

tints. Make a mixture of this powder with pure rock salt and cream

of tartar (bitartrate of potash), pulverized in the same manner as

described in speaking of silver-plating and take the same precautions

in its application.

The gold surface will present a dull appearance; acid cannot be used to

improve its color when operating, for example, on a wheel with attached

pinion, but the same result may be attained by a very simple method.

Rub the object after plating with cream of tartar, mixed with a large

proportion of water; then immediately wash in an abundance of warm

water at not less than 40° C. (104° F.); soap it thoroughly, so as to

neutralize any acid that may remain, and finally pass through alcohol

to dissolve any remaining soap.

The surface will be still further improved by rubbing with a very hard

piece of pith, such as is occasionally met with.

M. Robert, in describing the above method, adds: “In this manner I have

gilded cocks, domes, compensation balance weights, and even their brass

rims. When, skilfully and expeditiously performed, the pinion need

not be discolored; but, if it is at any time slightly marked, it may

be restored by at once rubbing the surface with a soft stick and fine

rouge.”

=143.= =Preparation of the gold powder.= As already observed this can

be obtained of any desired color from the dealers in chemical products,

but the following method is given for the benefit of any one who

desires to prepare it for himself:

Place some gold in thin leaves in a dish, and add a little honey,

thoroughly intermixing the two by the aid of a glass rod flattened

at one end; then place the paste so obtained in a glass of water

containing a little alcohol, washing it and allowing the powder to

settle. Decant the liquid and again wash the residue, repeating the

operation until a fine brilliant powder is obtained. This powder is

mixed as required with rock salt and powdered cream of tartar in the

manner already described.

=144.= _Second method._ Dissolve one part by weight (say about ten

grains) of pure gold, rolled very thin, in aqua regia (=155=) contained

in a porcelain dish, which may be gently heated on a sand-bath, and

evaporate the acid until it assumes a blood-red color. Add about

30 parts, by weight, of warm distilled water, in which 4 parts of

crystallized cyanide of potassium have been previously dissolved;

thoroughly stir the mixture with a glass rod, and filter it through a

glass funnel.

=145.= _Third Method._ Roseleur recommends the following solution for

gilding by simple immersion. Distilled water, 17 pints; pyrophosphate

of soda (in crystals) 28 ounces; hydrocyanic acid, 1-3 ounce;

crystallized perchloride of gold, 2-3 ounce. The pyrophosphate is

added, in small quantities at a time, to 16 pints of water, in a

porcelain vessel, stirring with a glass rod and applying gentle heat;

then filter and cool. The gold salt is dissolved in a small amount of

water; filter and add to the cold solution of pyrophosphate; lastly,

add the hydrocyanic acid and the solution, heated to the boiling point,

is ready for use.

The articles to be dipped must be thoroughly cleansed and passed

through a very dilute solution of nitrate of binoxide of mercury; they

must be constantly agitated while in the bath and the best coating is

obtained by dipping the articles in a nearly exhausted solution of the

same kind immediately after the mercury solution.

=146.= =Electro Gilding.= But the method most usually adopted is that

in which a battery is employed. It is, however, impossible, within the

limits of this work, to explain the precautions that are necessary in

conducting the process, managing the battery, etc., and the reader must

be referred to works on electro-metallurgy for these details.

=147.= =To prepare the pieces to be plated.= After the surface has been

stoned, boil the object a few minutes in a solution of soda or potash,

and rinse in clean water.

Roseleur, in the articles already referred to, gives very full

instructions, of which the following is an outline. The reader who

desires to obtain more complete information can consult his works.

Attach the pieces to a cork and brush with a clean brush charged with

water and pumice-stone powder and thoroughly rinse. Place them in a

solution consisting of: water, 2¼ gal.; nitrate of binoxide of mercury,

1-14 oz.; sulphuric acid 1-7 oz. Then rinse again.

=148.= =Graining.= Mix thoroughly with the application of moderate

heat, silver powder, 1 ounce; pure common salt, finely powdered, 13

ounces; cream of tartar 4 to 5 ounces. Make a thin paste of this

mixture with water and spread with a spatula on the pieces; having

mounted them on a cork to which a rotary motion is given, rub them

in all directions with a brush with close bristles, adding fresh

paste from time to time. When the desired grain is obtained, wash and

scratch-brush with revolving wire brushes. Three of these are often

used of varying degrees of hardness and a decoction of liqorice, weak

size or stale beer is liberally applied to the surface.

=149.= =Resist.= This is a composition for covering steel parts in

order to protect them from the action of the acids, etc., in the

various processes of cleaning, graining and gilding. It consists

of yellow wax, 2 ounces; clear resin, 3⅓ ounces; very fine red

sealing-wax, 1½ ounces; finest rouge, 1 ounce; Melt the resin and

sealing-wax in a porcelain dish, then add the yellow wax, and when the

whole is thoroughly liquid, gradually add the rouge, stirring with a

glass rod. The parts to be coated are slightly heated and covered with

the mixture.

To remove the resist after the gilding process is completed, place the

pieces in warm oil or turpentine, then in a very hot soapy or alkaline

solution and lastly in fresh water.

=150.= When prepared as above explained, the object may be gilt by one

of the preceding methods; of course a hot solution cannot be resorted

to when the resist has been applied.

=151.= =To clean objects that are of gold or gilt.= The following

method is equally applicable to pieces that are gilt, such as cocks,

domes, etc., the frames and parts of timepieces and to either gold or

gilt jewelry.

To about a tumbler of water add 20 drops of strong ammonia. Immerse the

object several times in this mixture and brush it with a soft brush; as

soon as the operation appears to be completed (which experience will

soon enable the workman to ascertain), wash in pure water, then in

alcohol, and dry with a fine linen rag. The original brilliancy of the

gilding will then be restored.

When the coating is thin and has been galvanically deposited, only very

soft brushes must be used.

Gilders, instead of dipping in alcohol and drying with a linen rag,

usually immerse the pieces in boxwood sawdust, leaving them long enough

to become thoroughly dry; after this treatment they merely require to

be shaken and lightly rubbed with a fine brush.

The sawdust must be perfectly dry; indeed it is a good plan to slightly

warm it by placing the wooden box containing it for a few minutes on a

hot oven or stove in the winter and exposing it to a hot sun in summer.

Instead of ammonia, alum (=156=) is sometimes boiled in water and

the objects dipped two or three times in this solution, subsequently

brushing as in the previous case.

=152.= _To restore the dead surface of gold or gilt objects._ Place

them for two or three minutes in chlorine water, rinse them in clean

water, soap them and finally dry in sawdust. It is advisable that parts

that are polished be prevented from actual contact with the liquid as

it would produce a somewhat deadened surface.

=153.= _To clean gold jewelry after soldering._ Particles of binding

wire are often left adhering to the surface of jewelry after soldering,

and, on dipping the object into the dipping liquid, a layer of oxide

may be formed. This can be removed without detriment to the polished

surface by plunging the object for a few seconds in nitric acid

(=155=).

ACIDS AND SALTS.

=154.= The watchmaker has occasion to employ a few acids and salts. He

should never forget the advice already given to keep them away from his

work-bench and always to well wash a piece of metal that has been in

contact with them.

=155.= =Acids.= _Nitric Acid_, either in a concentrated or dilute form,

will dissolve iron, steel, copper, lead, silver, zinc, brass, nickel,

mercury, German silver. It does not dissolve tin, but reduces it to a

white powder, known as metastannic acid. Hence, if an attempt be made

to dissolve bronze which contains tin, this metal is deposited, and the

copper and zinc pass into solution.

_Sulphuric acid_ will dissolve iron, steel, copper, tin, silver, zinc,

brass, nickel, mercury, German silver.

_Hydrochloric acid_ will dissolve iron, steel, zinc and nickel and has

a slow action on copper, tin, brass and German silver.

_Aqua regia_, a mixture of about 2 parts hydrochloric and 1 part nitric

acid, will dissolve all the above-named metals, and in addition, gold

and platinum, although separately neither acid will attack these metals.

_Hydrofluoric acid_ attacks and dissolves all metals, except platinum,

lead and silver with violent effervescence. It is also used for etching

on glass or enamel. It is usually preserved in gutta-percha bottles,

and is of such a dangerous nature that no use should be made of it

without a good knowledge of its properties.

Acids are rarely employed pure by watchmakers; they are diluted with

water. Nitric acid of commerce has a density of about 1.4 (38° on

Baume’s hydrometer). If this density is reduced by the addition of

water to 1.16 (20° Baume), we obtain the acid most commonly employed.

For cleaning metallic surfaces prior to soldering etc.; for giving

a grained surface to brass, and for whitening blue steel, special

proportions are found most convenient, which the reader can best

determine experimentally for himself, remembering that the action of

the acid should neither be too quick nor too slow. When once he has

ascertained the best proportion, he can always recover it by the aid of

the hydrometer.

=156.= =Salts.= _Borax_ serves as a flux in soldering gold, silver,

platinum, etc., (=131=); also for the same purpose in brazing (=138=);

it is met with in crystals or as a powder.

_Sal-Ammoniac_ (also called _Chloride of ammonium_), is used for

soldering tin, either as a powder or made into a paste, with sweet oil

or with water, or mixed with resin.

_Alum_ dissolved in water may occasionally be used in place of nitric

acid for cleaning surfaces that have been soldered; it attacks iron

or steel more energetically than copper, zinc, or brass. This fact is

often taken advantage of for removing broken screws, etc., from brass

plates. All other steel parts are removed and the plate placed in a

solution of alum, when the steel screw is gradually eaten away by being

converted into rust.

In 100 parts of cold water, only 9 parts of alum will dissolve, but if

the water be boiled, it will take up 75 parts. Its action will then be

proportionately more energetic when boiling.

OIL.

=157.= The oil intended for use as a lubricant for watchwork,

etc., should be kept away from the light, as otherwise it would be

discolored; it is on this account that the bottles containing such oil

are frequently covered with black paper. Only the quantity wanted for

immediate use should be placed in the oil-cup.

Two preliminary tests will afford some indication as to the quality of

an oil. A thick layer is placed on a small portion of the surface of a

glass plate, and side by side, a similar layer of another oil used for

comparison, and they are exposed to the air for some time without being

touched. The one that is found to be sticky under the finger when the

other has dried up will, in all probability, be preferable. The second

preliminary test is made on a whetstone; it is usually found that the

oil that takes the longest time to thicken is of better quality. Of

course these tests will only suffice to afford a rough approximation,

and cannot be accepted as conclusive.

The mode adopted for testing either the acidity or the purity of oil

will afford no evidence as to how long it will maintain its fluidity;

and very good results have at times been secured by the use of oils

that were slightly acid, or from mixtures of oils of two or more

qualities.

Many of the methods recommended for purifying oils are to a great

extent illusory, for they cannot impart to the fluid characteristics

that are wanting from the beginning. Success depends largely on the

skill of the manipulator; and if he is not endowed with the power of

judging, mainly by the taste, whether oil satisfies certain prescribed

conditions, he can never be certain of the result. Crops differ as

regards degree of maturity, etc., from year to year; and the animals

from which oils are procured are rarely in the same condition as

regards health, age, nourishment, etc.

Tests made on a whetstone, and on a window-pane, as well as

observations made on drops of oil placed in jewel holes, or in oil-cups

in a metal plate kept for the purpose—some of the drops being exposed

to the air, while others are in closed boxes—will afford valuable

indications; and according to the observations of M. H. Robert, it

is safe to consider an oil bad if, at the end of six or eight days

after being placed on a plate of good brass, it shows a marked green

tinge—especially so if a clearly defined fringe forms round the drop,

or else if the brass itself is discolored.

After all, the only evidence on which the watchmaker can rely is that

which he obtains by experimenting on watches which he keeps to lend to

his customers while their own are undergoing repair, and these trials

should last for at least a year.

And there is great variety among the wearers of watches. Some live in

constantly varying temperatures, often dusty; many ladies use perfumes;

some persons perspire more than others; all these causes influence the

oil, and make it alter or evaporate more rapidly in one watch than in

another.

=158.= =To secure the maximum permanency in oil.= In the case of very

many watchmakers who complain bitterly of the oils they employ, the

fault is their own and not that of the oil; for they neglect the most

simple precautions, both in purchasing and in using it.

The following are a few points to which attention should be given:

Do not buy, from motives of economy, bottles that have lain for years

in the shop.

Keep the oil away from the light, and only take in the oil cup the

amount required for immediate use, as stated above.

Ascertain that the watch-cases close well. If they do not, there will

be air currents generated, and the oil will suffer.

The oil in a cylinder escapement will always deteriorate very rapidly;

some watchmakers coat over the inside of the dome-joint and recommend

the owner not to open it. By doing so, the oil can be maintained in

good condition at the escapement for a long time.

Lastly, when cleaning a watch, the work should be conscientiously done.

This point is very important.

When the parts are carelessly cleaned with soap, or with impure

benzine, they will, after a few months, assume a dull colour, in

consequence of a thin layer of the materials used in cleaning having

been left on the surface. It has at times been noticed that steel work

was preserved from rust through the perspiration of the wearer, after

being cleaned by certain fluids. Evidently this was due to a thin

coating having been left on the surface of the metal. The conclusion to

be drawn is obvious: clean carefully; push the pivots into rather hard

pith; finish with a soft brush in proper condition, and clear out all

pivot-holes with pegwood.

=159.= =Mixed oils: camphorated oils.= Good results are frequently

obtained by mixing together two different kinds of oil. Thus, American

watch oil, which is very fluid and apt to evaporate at the temperature

of the pocket, is improved by the addition of a somewhat thicker oil. A

mixture of real American oil with the Rodanet oil has been recommended

as excellent.

There are some who advocate the addition of a small quantity of camphor

to an oil that is known to be satisfactory, but we cannot answer for it

from personal experience.

=160.= =Sinks.= In cleaning, it is important to avoid removing the

gilding in the oil sinks of watches, or the superficial oxide in the

sinks of clocks that have been going for a considerable time. For if

it be removed, there will be a fresh coating formed in time, and this,

too, at the expense of the oil.

In new timepieces that are not gilt, it is well worth while polishing

the sinks over their entire surface. If not applied too liberally, the

oil will then be more likely to remain in contact with the end of the

pivot. Moreover, as the surface is smoothed and hardened, and its pores

are, as it were, closed by the action of the polisher, the oil will

oxidize more slowly. This fact was first pointed out by Robin.

=161.= _Caution to be observed in applying oil._ The precautions to be

observed in applying oil will be better considered in Part V. of this

work, where we shall describe the method of cleaning and putting a

watch together.

=162.= =Retention of oil on acting surfaces.= Since oil is essential

in order to diminish friction, and the movement of the bodies to

which it is applied tends to drive it from the surfaces of contact,

it is important, with a view to its being constantly brought back and

maintained in proximity to these surfaces, that they be formed in

accordance with certain rules based on the laws of hydrostatics.

ALCOHOL.

=163.= Only what is known as rectified alcohol should be used in

cleaning parts of watch work. The copper pan in which it is made to

boil should not be too thin. The handle should be so arranged that it

can be fixed in the vise, and the lamp held under the pan.

When, in heating, the alcohol ignites, it is best not to attempt its

extinction by blowing; if the pan is held against the under side of

the bench, the flame will at once be put out, or this can be effected

by merely laying a piece of sheet metal over the pan. A good plan for

preventing ignition is to make a lid of wire gauze, which is placed

over the pan during the application of heat.

The substance known as “methylated spirit” is a cheap preparation

of alcohol, and of use for burning in a spirit lamp, and for other

purposes where the alcohol is not required to be pure.

BENZINE, ETC.

=164.= This and other preparations of a similar nature, such as Essence

Lemoine, Essence Genevoise, etc., are much used for dissolving clogged

oil and other substances of a greasy nature from parts of watches in

cleaning.

POLISHING MATERIALS.

=165.= The following account of the materials used for polishing, is,

for the most part, extracted from Holtzapffel’s _Turning and Mechanical

Manipulation_, to which the reader is referred for fuller information

in regard to them, and to their mode of application:

=Buff Leather= glued to a flat surface, or to the edge of a revolving

disc, is used with emery, crocus, rottenstone and other powders.

=Charcoal= is much used by steel and copper-plate engravers. That made

by burning elder without access of air is considered the best, but

willow and elm have also been recommended.

=Diamond=, in the form of powder, is used by lapidaries, seal

engravers, and watch jewel makers. The latter obtain the diamond

_bort_ that is rubbed off stones in faceting, and they separate it

into various degrees of fineness, by decantation (=168=). The mode of

applying it is described in articles =207=, =216=.

=Diamantine=, Sapphirine, Rubitine, etc., are names given to various

chemical preparations for polishing, to be obtained at the tool shops;

they must not be assumed to consist in any way of the jewels from which

their names are derived.

=Emery.= At the present day, oilstone dust is very frequently replaced

by emery with oil or water, especially in clockwork. Any required

degree of fineness can be obtained by decantation. Emery dust is

sometimes used in place of rouge for polishing.

The solid emery wheels and sticks, that are now common in the trade,

work rapidly, but they have the disadvantage of heating steel, and

many of them soon become pasty. The heating renders them less suitable

for grinding gravers, but they are very convenient for roughly shaping

steel work, or removing the hard surface caused by the application of

heat.

_To make emery paper._ If occasion requires it, this can be done as

follows: Fix a sheet of stout rope manila paper on a board, glueing

it round the edge. Having put emery powder into a sifter, the mesh of

which has the requisite degree of fineness, and rapidly covered the

surface of the paper with thin hot glue, shake the sifter lightly over

the paper until it is evenly covered, and leave to cool. When dry,

detach the paper and shake it vigorously to detach loose grains. Cloth

may be used instead of paper, if desired.

=Hone slates.= Under this heading are included a great variety of

stones used for smoothing and polishing.

_Ayr stone, or water of Ayr stone_, is much used for smoothing brass

work prior to gilding (=142=), etc. It should be kept wet in order to

prevent it from becoming hard.

_Blue polishing stone_ is much used by jewelers, clockmakers, and

others; it is recommended for use in spotting (=174=) and for polishing

wheels (=176=.)

_Oilstone._ This forms the quickest cutting whetstone known. Oilstone

slips are used by watchmakers after the manner of files. Oilstone

powder, or dust, is much used in the earlier stages of polishing, and

is preferable to emery in that it does not leave particles embedded in

the surface of the metal. On pewter laps it may also be employed for

polishing steel work.

_Oxides of iron._ Under this head are included the several materials

known as crocus, rouge, red-stuff, colcothar of vitriol, etc. It

is advisable to remove gritty particles from these materials by

decantation (=168=) before using.

_Pumice-Stone_ is extensively used for polishing cut glass, and is

applicable to brass and other metal work.

_Putty Powder_ is oxide of tin, or, more commonly, of tin and lead

in varying proportions. The whitest kind, provided it be heavy, is

considered the best.

_Rottenstone._ This variety of tripoli is of the greatest value for

polishing brass work, as well as for silver, glass, and even the

hardest stones.

_Tripoli_ is of a greyish yellow or red color, and consists mainly of

silica. Its principal use is in the polishing of hard woods.

_Whiting_ is common chalk, ground, washed to remove sand, etc., and

dried in lumps.

=166.= =Polishing Stones.= The following method is described by M.

Cadot for preparing these stones, which are very useful for polishing a

wheel that is not riveted to its pinion (see article =185=).

Carefully select a blue stone; after dressing its surface, smooth it

with emery paper of gradually increasing fineness. Saturate the surface

with oil, and rub it with a common piece of rough sapphire, one face of

which is flat and partly smoothed, until the surface of the stone is

hardened.

Such a stone is used dry. The wheels must previously have been

carefully smoothed, since the stone does not abrade the metal. If care

is taken to avoid scratches, the surface will last for a long time,

although, of course, it is only serviceable for gold, brass, nickel or

metals of a similar degree of hardness.

=167.= The several materials used for polishing must be kept carefully

packed (glass stoppered bottles are preferable), as a few grains of

dust, or of foreign bodies, will suffice to prevent the operation of

polishing from being successful. Polishers should be filed very smooth,

with a perfectly clean file that is not quite new. Files that are dirty

or new will deposit small hard particles of dirt, or cause pieces off

the points of their teeth to become embedded in the surface of the

polisher.

PREPARATION OF POLISHING MATERIALS.

=168.= =Decantation.= This consists in causing a material in a fine

state of sub-division to fall slowly through a liquid with the view to

separate coarse particles, or various degrees of fineness, by taking

advantage of their different rates of descent.

The watchmaker should prepare all his smoothing and polishing

materials, etc., by decantation. He will by this means obtain them in

grains that are much more uniform in size, of any required degree of

fineness and free from hard or large particles.

[Illustration: _Fig. 40._]

The operation is exceedingly simple. The material having been pounded

under the hammer or otherwise, is thrown into a vessel more or less

filled with a liquid, water, oil, etc. After being thoroughly stirred,

it is allowed to partially settle, and the liquid is carefully poured

into another vessel. All the coarse heavy grains will be found as a

residue in the first vessel; they are collected and used for coarse

work. After again stirring and leaving to settle for a longer period,

the liquid is again poured off, and the powder thus separated will

be the second degree of fineness, so that it may be termed No. 2. By

successive operations, in which a gradually increasing interval of time

is allowed, Nos. 3, 4, etc., can be obtained; that is to say, a series

of powders of the same material but presenting a greater degree of

uniformity in the size of grains and of gradually increasing fineness.

It may be observed that when the powder of the requisite degree of

fineness is nearly attained the mass should be left to settle until

the following day, or, rather, until the fluid is clear; then decant

carefully so as not to lose any of the deposit.

When treating a material that is soft and friable, it should be crushed

between the fingers, as by using a hammer hard grains of foreign

matter might be accidentally intermixed. Oil may be used for decanting

diamond powder or oilstone dust for smoothing; water for rottenstone or

tripoli; alcohol for hartshorn, etc.

=169.= =To prepare diamond powder.= Select rough diamonds of a blackish

tint, of such a size that there are four or five to a caret. These are

crushed in a hard steel mortar of the form indicated in fig. 40, the

pestle being provided with a small stuffing box that can be brought

down on to the mortar to prevent the escape of diamond-dust; but it is

well to first crush one stone, with a single blow of the hammer on the

pestle; remove all the fragments and examine the end of the pestle;

it will be found that a number of particles have bedded themselves in

it; these should be examined to select pieces to serve as drills and

gravers. The larger fragments serve for gravers, and particles should

be sought that are as nearly as possibly triangular prisms about

¹⁄₅₀ inch long for making drills. The other stones may be treated in

similar manner till enough fragments are found. Now place all other

pieces in the mortar, and continue for two or three hours striking the

pestle with the hammer, turning it partly round after each few blows

to prevent the powder from imbedding itself in the steel. When no

“bite” is perceived in rotating the pestle, the diamond is sufficiently

reduced; it is shaken out of the mortar into a watch-glass containing

the most limpid oil attainable, and if necessary the fragments are

released by a steel spatula, at the same time striking the external

surface of the mortar with the hammer. Thoroughly mix the oil and the

powder, subdividing the latter as much as possible by rubbing against

the glass with a spatula; allow the mixture to rest for an hour and

pour off the liquid into a second glass, leaving the larger particles

behind. Leave the oil in the second glass for four hours; then decant,

into a third glass with the same precautions; this is left for eight

hours; the next glass sixteen hours. When all the powder has settled

pour off the oil, and the several degrees are ready for use.

Some jewelers prefer to leave the powder for two or three days in

a mixture of equal nitric and sulphuric acid in order to dissolve

particles of steel. The acids are then much diluted with water, left

for some days and decanted. Then wash the powder in two fluid ounces of

pure alcohol, leave for two days, decant and dry, and afterwards treat

with oil. The operation is long and hardly necessary.

SMOOTHING.

=170.= If a surface is smoothed well, the labor of polishing will be

diminished by at least one-half, and it is an essential preliminary if

a good gilding on brass is required.

The materials most frequently used are emery and oilstone dust for

steel, pumice and water of Ayr stone for brass. The stones should not

be traversed by veins, nor exhibit hard grains. Powders should be

freed from large or hard grains by decantation, and it is advisable to

repeat this operation several times in order to have several degrees of

fineness.

SMOOTHING OF BRASS.

=171.= Every watchmaker knows that after finishing the object with a

smooth file, it is smoothed, first with a blue stone or rather coarse

water of Ayr stone, and then with one of finer grain. If the brass

is to be gilt, the operation is concluded with a series of circular

strokes, so as not to leave any striæ or bright spots; if the surface

is to be _spotted_ or watered the final strokes should all be parallel.

A soft piece of charcoal applied with water may also be used on objects

intended for gilding; in other cases it is used with oil.

=172.= =Wavy or watered smoothing.= This is done with water of Ayr

stone and oil carefully prepared, or with a piece of wood charged

with oilstone dust, etc. The oiled corner of an emery buffstick can

occasionally be used.

To obtain wavy undulations on a smooth piece of metal, the finger

should first be placed at the point of commencement of the undulations.

Resting the wood or stone against the finger, it is moved a little in

a straight line, and then in a series of semicircular waved lines,

from right to left or left to right. The finger is advanced through a

definite distance and the operation repeated, and so on.

A very good watered surface can be produced with soft charcoal. With a

view to increasing the regularity in the marks, a rule may be laid on

the object, against which the charcoal is brought.

[Illustration: _Fig. 41._]

Parallel watering is usually done mechanically, but any watchmaker can

secure regularity by the following simple device.

Fix a graduated rule _t g_ across the cork (fig. 41) and two pins A A,

to form stops for preventing the stick or stone from traveling too far.

A division of the rule is made to correspond with the line _v v_; and,

when the first line has been traced, advance the object by one, two or

three graduations of _t g_, according to the interval that is to be

left between successive undulations. Then trace the second wave, and so

on.

=173.= =Wavy and curvilinear smoothing.= These are of two kinds; some

are entire circles, which we shall proceed to consider; others radiate

in curves from the circumference to some other point of the circle

as, for example, many of those that are met with on keyless ratchet

wheels. The latter will be discussed farther on, when discussing the

smoothing of steel, for the process is identical for both steel and

brass, except that with the latter named metal and nickel the stick may

be replaced by a strip of zinc or tin, and coarse rouge is used.

=174.= =Circular snailing or spotting.= This is produced on a special

tool by which several motions can be given to the object, but

watchmakers, as a rule, so seldom have occasion to trace this class of

ornament, that it will suffice to explain how it can be produced by the

appliances that everyone has at hand.

The universal mandrel may be employed for the purpose, but, in that

case, the operation is a very slow one, whereas, with the ordinary

lathe, it can be done both rapidly and well.

[Illustration: _Fig. 42._]

Adjust a rest of the form shown at s (fig. 42), taking care that the

height of the center is sufficient; the small rectangular bed _a a_ has

a projecting edge, divided by equidistant graduations. To the headstock

of the lathe is attached, at _b_, a piece of bluestone or wood. Having

set the rest at a convenient height, and holding the object to be

spotted, P, on the rest, bring in it contact with _b_ when in rotation.

When the mark is made, lean the object from _b_, slide it along _a a_

so that its edge coincides with the next division and make another

mark, and so on until an entire row is completed. Then raise or lower

the rest and repeat the process for a second row, and so on.

Instead of applying oil to the acting face of _b_, which would have to

be renewed at each operation, it is usual to cover the object P with

oil, if _b_ is a stone, or with oil mixed with the substance used for

smoothing, if _b_ is of wood. If this precaution is taken, the work

will progress much more rapidly.

When the object operated upon is of irregular shape it must first be

attached to a rectangular plate and then proceed as already stated.

A still more simple method, but one that is, in certain cases quite

sufficient, consists in passing through the poppet-head a center of the

form _f d_ (H, fig. 42) which is caused to rotate by the fingers or any

other means.

[Illustration: _Fig. 43._]

To make spottings that, instead of being parallel, radiate from the

center to the circumference, the rest _a a_ must carry a disc that can

rotate on a clamping screw, and is maintained in position by a finger,

with an even number of equidistant divisions on the circumference of

the disc. The object to be operated upon is then fixed to the disc, and

a stick used, the diameter of which is equal to the distance between

two radii that pass through a pair of graduations on the disc; for

example, the small circle _s_ (fig. 43). A series of circular spots is

then made by gradually rotating the disc. Now replace the rod _s_ by

one of the diameter _n_; advance the support until it corresponds with

the position _n_, and make the second range of circular spots, and so

on. The figure renders any further explanation unnecessary.

The watchmaker who has clearly followed what precedes will be able,

should occasion require it, to construct a special tool acting with

certainty; but it will be well to remember that there is a great

advantage in driving the spotting stick by the foot, and bringing it

down on the object by a small hand lever, after the manner of the

drilling machines used in factories.

SMOOTHING OF STEEL.

=175.= The smoothing of a steel object is commonly done on a piece of

cork, with a large iron polisher charged with oilstone dust and oil. If

a flat surface, it can be finished with a copper polisher or on a sheet

of glass. In the case of staffs, arbors, etc., that are not intended

to be polished subsequently, a certain degree of brilliancy is given

to the surface by rubbing with wood, usually pegwood, or with a stick

covered with the finest emery paper and oil.

A surface that will not be subjected to friction—as, for example, the

head of a screw—can be smoothed rapidly and well with a dry emery

buffstick if little metal has to be removed, and the polishing can then

be at once proceeded with. Only one cleaning is in this case necessary,

for after the emery it will suffice to rub with pith and pass a brush

over the surface.

For ordinary work, smoothing a staff or head of a screw with dry, fine

emery and finishing by the friction of rather hard pith backwards and

forwards, will give a fairly satisfactory surface.

=176.= =White and dead smoothing.= To produce a graining, the piece of

steel must be previously smoothed in the ordinary way, perfectly flat

and free from scratches. The graining is produced by rubbing the object

on a sheet of ground glass with the finger, taking very small circular

strokes, especially towards the end of the operation. The degree of

success depends on the quality of the oilstone dust employed. It must

be very fine, and it will be a prudent precaution to decant the powder

in water, or preferably in oil, and not to use the earlier deposits

(=168=).

When the oilstone dust is not very good, it may be washed in

hydrochloric acid, which dissolves most of the hard grains, but it will

require to be thoroughly washed in water afterwards, on account of the

difficulty there is in removing the last traces of the acid. Of course

such a method is only to be resorted to on an emergency.

Perhaps the most difficult piece to grain is a keyless barrel ratchet,

because if the operation is at all prolonged the edge of the ratchet

may become white before the center and it may even polish. If this

happens, the ratchet should be held in the hand and rubbed with a piece

of pith cut to a blunt point with a flat end. By this means it is easy

to act on the center, avoiding the edges.

=177.= =Dead white or frosted surface.= After having grained the steel

in the manner above indicated, if it is required to obtain a dead white

frosted surface, employ a mud formed of Arkansas stone dust, or the

sticky deposit on a whetstone, which is more easily obtained. It should

not be too yellow, as the result is all the better according as a

greater number of steel particles are mixed with the oil; at least, so

we are informed by some very good workmen. A large piece of elder-pith

having been divided into two equal parts lengthwise, is smoothed with a

new, clean file; the mud is spread upon it, and the piece of steel is

moved over it with circular strokes as in producing the graining. In

this case the movement can be rapid. If the operation be well done, and

if the oilstone dust used be of good quality, the object will, after

being cleaned, present a beautiful uniform white surface in which the

graining is still visible. Experience and knack are everything in the

proper conduct of such an operation, especially in its concluding stage.

The surface may be cleaned in pure benzine mixed with a little

sulphuric acid, followed by a very clean buffstick, which will impart a

brilliancy to the metal.

M. Bean recommends fine Turkey oilstone powder mixed with turpentine

as the best preparation for rapidly producing a dead smooth surface on

steel work.

Workmen that are constantly engaged in graining employ a foot-wheel for

the purpose. The ground glass is fixed so that, although not rotating,

a small circular motion is communicated to it. The steel is then simply

held against it; indeed, several pieces can be grained in this manner

at once.

To the methods above described we would add the following, which is

successfully practiced by several English workmen:

They lightly fix the ratchet, for example, by its edge, and finish the

smoothing with a piece of pith, more or less charged with pure charcoal

powder and fine oilstone dust. Here also knack is mainly instrumental

in insuring success.

=178.= =Snailing.= To produce the snailing on a fusee or on keyless

wheel-work, the device shown in fig. 44 can be used. The ratchet or

fusee is mounted between one pair of centers and driven by a cord

from a foot or hand-wheel. The copper or iron lap, having a diameter

equal to about three times that of the surface to be snailed, is

charged with fine emery powder and oil, or oilstone dust, etc., and

set in contact with the face of the steel, which thus causes it also

to rotate. The direction of the snailing will be the same, whether

the rotation is to the right or left. If it be required to change the

direction, the relative positions of the two pieces must be reversed.

It has been already observed that brass and nickel can be snailed in

the same way, employing a zinc or tin lap and coarse rouge (=173=). In

some cases, hard wood laps can be used for these softer metals.

In keyless steel wheels a beautiful snailing can be obtained with

Arkansas stone mud (or, in its absence, the greasy mass from an

oilstone) mixed with polishing rouge.

[Illustration: _Fig. 44._]

With reference to the little tool shown in fig. 44, it may be observed

that, if the axes of both the steel piece and lap were driven by bow or

otherwise, the surface would be polished and not snailed.

In the absence of the tool here referred to, any one can easily

construct one for the purpose which will adapt to the mandril or a

foot-lathe: in order to help him in doing so we will describe one

designed by M. Cadot, of Paris.

=179.= _Tool for snailing._ This is shown in fig. 45, and we would at

the outset observe that it can be used equally well for polishing. To a

shoulder at the extremity, A, of a piece of steel rod, B (which takes

the place of the slide-rest cutter) is riveted an L-shaped piece _c

c d_, and to the point _d_ is firmly fixed by a screw or rivet, the

upright piece _d h_ parallel to _c c_; this piece is enlarged at _h_ so

as to give a bearing to a hardened steel screw, with a hollow point, in

the axis of B: the lap is supported between this screw and a hole in

the center of A. The figure will suffice to indicate the form of this

lap which is dished internally as shown by the dotted line. It is made

of iron or copper if intended for use with hardened steel.

[Illustration: _Fig. 45._]

The piece to be snailed is fixed to a chuck of the foot-lathe, and,

having fixed the rod B in place of the cutter, the lap is brought, by

means of the slide-rest screws, in contact with the steel, taking care

not to set it up to the center, as snailing that starts from the center

is not so good. Having charged the lap with fine emery and oil, the

object is rotated and it sets the lap also in motion.

It was mentioned above that this tool can be employed for polishing:

for such a purpose use fine rouge, replace the lap by one of bronze or

bell-metal, fix a ferrule at _i_, and, while the object turns in the

lathe, rotate the lap with a bow.

By fixing a rod at L instead of at B, the tool is at once adapted to be

used in an ordinary pair of turns, as it can be fixed in place of the

T-rest; but it is not so easy to secure parallelism of the two surfaces.

=180.= =To restore the watered surface in nickel movements, etc.=

Although the following is employed for nickel (or rather German silver)

it may be well to observe that it is equally applicable to all other

metals.

As these nickel movements are not gilt subsequent to being repaired,

it frequently happens that the water marks on the surfaces do not

correspond. By the aid of the following device watchmakers can correct

this fault, but we must warn them that, as in all operations involving

dexterity, they must first make experiments in order to acquire the

requisite manual skill.

[Illustration: _Fig. 46._]

On a small open frame C C, fig. 46, fix several parallel bars _f l_,

_e d_, etc., and on two of these adjust a slide _p o n m_, with two

strips glued underneath so that it can travel up and down between _a_

and _b_. On _p o n m_, fix a guide of convenient form, as G; and, after

cementing the piece, say A, that is to be watered on a board resting

on the bench, place the frame C C above it and trace the figure of the

guide with a pegwood stick charged with polishing material. The same

figure can be reproduced in parallel rows as the guide can be moved up

or down.

By varying the shape and position of the guides, the water lines can

take the form of waves, festoons, circles or ovals. In the two latter

cases the guide has apertures of the requisite form, and the board that

carries A, not being more than half the size of the aperture, can be

moved about by hand or by a tool.

If preferred, one of the bars, as _e d_, can be graduated and

arrangements can be made for clamping the slide by screws in any

position.

These explanations will suffice to enable any intelligent watchmaker,

after a few trials, to imitate successfully any of the beautiful

watered surfaces that are, on a manufacturing scale, produced by

machinery.

As regards the material to be used, first mix medium rouge and putty

powder in equal proportions. It will be possible to decide from the

shade obtained whether more putty powder should be added, because when

there is too much rouge, the surface does not acquire a good white

color.

POLISHING.

=181.= =To polish brass.= When it is required that a surface be

maintained perfectly flat, first dress with somewhat coarse water of

Ayr with blue stone and then go over with a softer stone. Next work

with fine rottenstone and oil on a felt or buffstick for objects of

large dimensions and on a piece of pegwood for smaller articles. They

are then soaped, washed and dried in sawdust (=151=).

The work can be accomplished more rapidly, but without maintaining

a perfectly flat surface, by first employing pumice-stone and oil

spread over a large piece of soft wood or felt. It is then cleaned and

polished with rottenstone.

When the form permits of it, a tin disc charged with tripoli and

rotating in a lathe can be employed.

_Observations._ Pumice-stone is powdered fine and then sifted. In using

rottenstone a piece an inch or two cube is crushed between the fingers

into a cup of water, and this is decanted so as to give several degrees

of fineness (=168=). The polishing can best be effected by using old

wood from which the sap has dried up: French chalk has but little

action if the polisher with which it is applied is from the animal

kingdom, horn for example, etc.

=182.= =To polish watch wheels.= Although the operation of polishing is

extremely simple, it is very important that a certain degree of manual

skill be acquired by practice, as otherwise the work is never of the

best.

We will here enumerate several methods of procedure, in order that,

after trial, each can select the method with which he finds himself

most successful.

_Smoothing._ The smoothing should be done carefully with very soft

water of Ayr stone, free from veins and hard grains and perfectly

flat. The wheel must then be well cleaned.

_Polishing._ In polishing, rods of walnut or boxwood, of tin, bronze or

zinc are used. A buffstick and burnisher are also employed.

The materials applicable are rottenstone (with oil or alcohol, being

made very thin in the latter case) tripoli, prepared chalk, polishing

rouge, crocus, etc. These materials have been sufficiently described in

articles =165-7.= Workmen sometimes prefer to make mixtures of two or

more substances, but it is more usual to employ them separately.

=183.= _First Method._ After smoothing and cleaning the wheel, it is

polished while resting on a piece of cork, where it is held between

the fingers which cause it to rotate; the best rottenstone is used

and is applied by smooth pieces of boxwood, about 8 inches long,

which are filed to a bevel edge. It is best to have the grain of the

wood crosswise and the polishers should be of sufficient thickness to

prevent their bending when in use.

The rottenstone can be replaced by tripoli and the boxwood by walnut.

Some wheel polishers prefer a triangular stick of pure tin or zinc

which is often planed to ensure perfect flatness; rouge, rottenstone or

tripoli can be used with it.

The wheel, after being well washed in soap and hot water, is thoroughly

dried and finished with a fine buffstick in good condition, while it

rests on a cork covered with smooth felt; this operation is with a view

to prepare the surface prior to using the burnisher.

Some polishers, instead of the dry buffstick, prefer one charged with a

little rouge, tripoli or rottenstone moistened. But such preparations

must be applied very sparingly as they involve a risk of rounding the

edges.

The burnisher is next rapidly passed over the surface of the wheel,

which rests on cork, covered with a linen rag, or on a piece of wood,

covered with smooth paper. Some give long backward and forward strokes

with the tool; others give semicircular movements. It will be found

sufficient to give short strokes from half an inch to an inch in

length. A slight motion of the wrist is all that is required and after

a few trials the necessary skill will be attained. We cannot say more.

Practice must also be relied on for determining the most suitable

pressure.

The burnisher, about half an inch wide and four inches long, is curved

in the direction of its length. A straight burnisher might be used,

but it is less safe; the angle of the burnisher set against the pinion

should be rounded off.

The burnisher is cleaned and restored by drawing across a large flat

piece of walnut charged with rouge of very good quality and very pure.

After being washed, a little white wax is passed over it, and then

it is again rubbed vigorously with a piece of cloth or a buffstick;

finally with a soft linen rag. When a tendency to stick shows itself

this operation must be repeated.

=184.= _Second process._ By this method the surfaces are somewhat

rounded off at the edges. But, although not so pleasing to the

eye, this circumstance involves no inconvenience except that, when

burnishing, the burnisher would not at once come in contact with the

entire surface; we need not, however, employ the burnisher.

Laying the wheel on a cork, some workmen smooth the wheel by covering

it with oil and fine tripoli and rubbing with a walnut-wood stick.

Others spread a layer of such a mixture first on the stick and then

rub the wheel. When no more lines are observable across the surface of

the wheel it is cleaned, placed on a fresh cork that is covered with

a soft linen rag, and polished with a fresh buff stick (or one that

has already been used for a similar purpose) and an abundant supply

of rouge or even fine rottenstone and oil may be used. The buffstick

receives a semicircular movement in all directions in order not to

needlessly round the corners, the edges of the teeth and the crossings.

It is then washed in warm water, bathed in alcohol and dried with a

fine linen rag.

=185.= _Third process._ After smoothing with a very soft stone, rub it

with a piece of the root of boxwood cut across the fibre, on which is a

layer of the following composition:

Two-thirds rottenstone mixed with one-third castile soap, worked into a

paste with a few drops of water so that, although not a liquid, it can

be spread out at will.

Make the wheel move backwards and forwards between the fingers while

resting on a smooth, good cork, without a linen rag, and, as the

operation nears its completion, a semicircular motion should be given

to the wood. Wash with soap, boil in alcohol and dry.

The wheel can be burnished on a cork without any linen rag and the

(curved) burnisher should be moved with short circular strokes from the

center towards the circumference, gradually working up towards to the

extremity of the burnisher; the same portion of the burnisher should

not pass twice over the wheel (see also article =166=). For common

work, fairly satisfactory results may be obtained by using French chalk

and a piece of hard wood.

Clock wheels are polished with a piece of felt and rottenstone. They

are subsequently soaped, washed and dried in sawdust. (=151=)

=186.= =To polish lever escape-wheel teeth.= The Lancashire

escape-wheel makers employ a triangular frame carrying at its corners,

(1) a cutter to slit the teeth, (2) a cutter to shape them, and (3)

a revolving piece of hard leather of a section corresponding to the

form of the space. This latter is charged with the finest glossing

stuff, used dry, and the sides of the teeth of six wheels at a time are

polished by revolving the disc in each of the spaces in turn. It is

hardly necessary to observe that the operation is completed before the

wheels are removed from the cutting engine.

=187.= =To polish sinks or oil-cups.= A piece of pegwood, rounded at

the end, is used for this purpose, rotating it in a lathe; the watch

plate or cock should be inclined in varying directions to the stick in

order to remove scratches. If a very high polish is required it may

be given by following with a stick, the end of which is covered with

wash-leather charged with rouge.

TO POLISH STEEL.

=188.= The polishing must always be preceded by a very thorough

smoothing, either with oilstone dust, fine emery, or coarse rouge. If

any lines are left to be erased by means of fine rouge, the operation

becomes tedious and is rarely successful. The oilstone dust is applied

on an iron or copper polisher. When it is desired to preserve the

angles sharp, at a shoulder for example, the polisher should be of

steel.

When using diamantine an iron polisher, drawn out and flattened with a

hammer, answers very well.

With fine rouge, a bronze or bell-metal polisher is preferable

for shoulders; and, for flat surfaces, discs or large zinc or tin

polishers, although glass is preferable to either of these.

After each operation with oilstone dust, coarse rouge, etc., the

polisher, cork, etc., must be changed, and the object should be well

cleaned—preferably by soaping; perfect cleanliness is essential to

success.

Fine rouge or diamantine should be made into a thick paste with oil; a

little is then taken on the polisher or glass and worked until quite

dry. As the object is thus not smeared over, a black polish is more

readily obtained, and the process gets on better if the surface is

cleaned from time to time.

=189.= =To get a good black polish.= As just pointed out, this is

mainly secured by using very little polishing material at once, in a

very little liquid on either, the polisher or glass plate and drying

up quickly. If the surface does not prove satisfactory at first,

it will often be found that a final rapid and light application of

dry diamantine or rouge on a piece of glass or pith will produce a

brilliant black polish.

If operating on an axis or staff, polish as well as possible, first

erasing the marks of the graver or file, and then, hold the ferrule

between the fingers, rotate it with one hand and with the other rub the

axis lengthwise with a pegwood stick charged with rouge or diamantine.

A rod will show a black polish if it be rubbed lengthwise with emery

paper of gradually increasing fineness, oil being applied with the

finest quality.

_To polish flat surfaces._ Place the object on a sound piece of cork

covered with a clean rag and rub with, a long strip of ground glass.

_To polish a square shoulder._ Fix a rod in place of the T-rest of

the turns, and set it in such a position that the polisher rests on

this vertical rod when lying flat against the shoulder. Another and

better method consists in cementing or otherwise fixing in the plane

of the shoulder a brass disc of such dimensions that the polisher is

constrained to remain flat.

_Observations._ The corner of the polisher that is used for polishing

a shoulder should be neither right-angled nor too acute. In the first

case it would round off the shoulder, and in the second it would become

soon distorted and leave dull radial marks on the surface.

Diamantine should not be used for polishing the acting surfaces of

pivots, the pallets of escapements, etc., since this material, as well

as emery, is liable to leave particles embedded in the steel which

occasion rapid wear.

CEMENT, WAX, RESIN, ETC.

=190.= The principal uses to which the watchmaker applies cement is

for fixing objects in the lathe, pallet-stones in position, as well as

locking and unlocking pallets, ruby-pins, etc.

The selection of a cement or wax is not a matter of indifference;

fine sealing-wax causes objects to adhere firmly together, but many

of the best workmen prefer refined shellac. Certain kinds of wax are

too dry, the consequence being that a false stroke of the graver will

often detach the piece; others are thick and soft, and are apt to heat

rapidly under the action of the burnisher or polisher, so that the

object is displaced. It is only by making a series of trials that the

efficiency of the material can be ascertained. Some workers claim that

a mixture of sealing-wax and shellac gives good results.

=191.= =Mode of applying cements.= When employing wax, resin, cement,

etc., for uniting two objects, it is important to note that the mode

in which it is applied has an important influence on its efficiency.

The following observations on this point are due to M. Sibon, and the

reader will be able to select those portions that have reference to his

work.

When two objects are united by a cement, this will lose much of its

value if unskillfully applied, and, in order to use it to the best

advantage, the following practical rules should be observed.

1. The surfaces to be united must be quite clean.

2. The less cement, wax, etc., that is interposed between them, the

better they will adhere. This is owing to the fact that with a thick

layer the object has, at the junction, no more rigidity than that of

the cement itself; as a rule this more fragile than the material it is

employed to unite.

3. There should be perfect contact between the cement and the surfaces.

With a view to securing this, the object must be first heated to a

point such that the wax or cement cannot solidify without having first

had time to effect a perfect union.

This remark is especially applicable when using sealing-wax, mixtures

of resin, shellac, and similar materials. They will not adhere firmly

unless the surfaces have been heated very nearly to the point of fusion

of the cement. The sealing of letters offers an example in proof of

this assertion. When the seal has been used several times in succession

or been left too long on the wax so as to become hot, it will adhere

and cause some inconvenience if further employed.

With hot melted glue, adhesion is best secured by friction or a

moderate pressure.

Sealing-wax is excellent for uniting metal to glass or stone, providing

they are sufficiently heated to melt it; for, if applied to cool

surfaces, it will not adhere at all. By heating two pieces of glass or

stoneware sufficiently to melt shellac, a small quantity will suffice

to make them adhere firmly together; notwithstanding that every one

has seen such joints, very few succeed in making them, for the simple

reason that they do not recognize the necessity of heating a delicate

piece of glass or china to the point which is essential for securing a

good result.

In conclusion, the principal obstacles to adhesion are air and

dirt. The first is always present; the second is due to accident or

carelessness. All surfaces are covered with a thin layer of air that is

very difficult to remove; its influence prevents highly polished metal

from being moistened when immersed in water. So long as this layer of

air is not displaced, the cement cannot adhere to the surface to which

it is applied, because it cannot come into direct contact. The most

effective agent for displacing this air is heat. Metals heated to about

75° C. (170° F.) are immediately moistened on being plunged into water,

hence it follows that, as regards cements that are applied in a fused

state, heat is the best means of bringing them into intimate contact

with the surface.

We would add that, in addition to possessing this advantage, the

application of heat also renders the surfaces more penetrable to

the layer of cement, after the manner of soldering, and makes the

interlocking of the molecules more perfect; this explains the greater

degree of tenacity of a well made joint with only a thin layer of

cement.

=192.= =To set in wax in the lathe.= Trace a series of concentric

circles on the face of the chuck with a graver point, after turning it

true: this will increase the adhesion of the cement. Then the flame of

the spirit lamp is held under the rotating chuck and, when this is hot

enough, its surface is covered with a layer of shellac or sealing-wax,

and the object is held against it. Holding it in position with a piece

of pegwood supported on the T-rest, the lamp is removed and the lathe

kept rotating until the cement sets. The cooling can be hastened by

applying a small moist sponge, but it should not set too suddenly.

If the object requires to be very exactly centered, its position must

be insured while the cement is still soft by means of a long pegwood

stick in its central hole. This stick is held in position until the

cement sets, steadying it between two fingers close up to the chuck.

The slightest eccentricity will be indicated by a motion of the free

end of the stick.

If the object is round, and has no central hole, it must be centered

by its circumference, holding the pegwood in front, or resting against

a corner of a circular elevation or depression, as, for example, the

collet of a wheel, or of a cylinder riveted to its balance, etc.

The beginner should make a number of trials; they will enable him both

to acquire lightness of touch, and to recognize the proper degree of

softness of the cement for centering, as well as its tenacity.

When it is essential that the two faces of the object be strictly

parallel, a precaution is necessary; this consists in leaving on the

face of the chuck a slightly projecting circular rim with a fine smooth

edge, and of a diameter rather less than that of the object. By moving

this latter backwards and forwards after applying it to the wax, and

pressing it into close contact while cooling, the requisite parallelism

will be secured.

=193.= =To fix a pallet-stone, etc., in position.= To fix a

pallet-stone or an end-stone by means of shellac it is usual to place

a small piece of the latter round the stone when in position and

apply heat. But very often the lac spreads unevenly or swells up; and

this, in addition to being unsightly, is apt to displace the stone.

The inconvenience can be avoided as follows: The pallets are held in

long sliding tongs, and, taking a piece of shellac, heat it and roll

it into a cylinder between the fingers; again heat the extremity and

draw it out into a fine thread. This thread will break off, leaving a

point at the end of the lac. Now heat the tongs at a little distance

from the pallets, testing the degree of heat by touching the tongs with

the shellac. When it melts easily, lightly touch the two sides of the

notch with it; a very thin layer can thus be spread over them, and the

pallet-stone can then be placed in position and held until cold enough.

The tongs will not lose the heat suddenly, so that the stone can easily

be raised or lowered as required. The projecting particles of cement

can be removed by a brass wire, filed to an angle and forming a scraper.

To fix an end-stone, the cap must be held by its edge in the sliding

tongs, and shellac carefully applied around the edge of the hollow. It

is advisable to hold the cap in a small tool formed of two parallel

blades, as when reversed so as to press the stone on a flat surface,

the shellac will spread over the end-stone, from which it will be

removed with difficulty.

ENAMEL.

=194.= This name is applied to an opaque glass, with which various

metallic compounds, such as oxide of tin, phosphate of lime, borax,

etc., have been incorporated by fusion. The color, of course, varies

with the substance so added.

Willis recommends the following as a good white enamel for dials:

silver sand, 14 parts; borax, 10 parts; red lead, 18 parts; niter, 2

parts; oxide of tin, 12 parts; flint glass, four parts; and binoxide of

manganese, 1-50th of a part. But a good deal of care is requisite, both

in selecting the materials and preparing the enamel, in order to insure

a pure color of any desired shade; it is, therefore, often desirable to

purchase the enamel ready prepared.

In applying enamel, regard must be had to the relative dilatation of

the metal to which it is applied, the two being so combined as to

expand and contract together; otherwise there is danger of the enamel

cracking, either at once or shortly after it has set.

Enamel may be applied to gold or copper. Associated with the latter,

it forms the ordinary dials of watches and timepieces, and, with the

former, it serves for making enameled gold dials or cases. The gold

should be of 22 carat, the 2 carats of alloy consisting of equal parts

of silver and copper. If the gold is of a higher standard, it will

not adhere so well, and, if lower, there will be a further danger of

melting the metal before the enamel is fused.

Silver is apt to cockle on the application of heat, and enamel applied

to it presents a bubbly appearance.

=195.= =Application of enamel in the cold.= We are indebted for the

following particulars to M. Fournier, of Dieppe, a well-known enamel

maker:

There are two kinds of false enamel for application, when cold, to

damaged dials.

The first, a mixture of white resin and white lead, melts like

sealing-wax, which it closely resembles. It is advisable, when about to

apply it, to gently heat the dial and the blade of a knife, and, with

this, to cut a piece of enamel of the requisite size and lay it on the

dial. The new enamel must project somewhat above the old. When cold,

the surface is levelled by scraping, and a shining surface is at once

produced by holding at a little distance from the flame of a spirit

lamp. It is necessary to be very careful in conducting this operation,

as the least excess of heat will burn the enamel and turn it yellow; it

is, however, preferable to the following, although more difficult to

apply, as it is harder and does not become dirty so soon.

The second false enamel contains white lead mixed with melted white

wax. It is applied like a cement, neatly filling up the space, and

afterwards rubbing with tissue paper to produce a shining surface; if

rubbed with a knife blade or other steel implement its surface will be

discolored.

PRECIOUS STONES.

=196.= The principal precious stones used in watches, chronometers

and regulator clocks, in their order of hardness, are: diamond, ruby,

sapphire, chrysolite.

A watchmaker, although he may not have had any previous experience

of jewels, can easily ascertain their relative hardness by rubbing

one against the other. The softer will be scratched by those that are

harder, and the stone that can be marked by a file may be thrown aside

as useless.

=197.= =Diamond.= We shall make a very brief reference to this

stone, as it is not used except for the end-stones for balances for

chronometers and high-class watches.

Splinters of diamond are employed for drilling materials of a less

degree of hardness, and fragments fixed at the end of a rod are used

for turning very hard steel; diamond dust is the principal material

used for working precious stones, polishing, etc. (see articles =165=

and =169=).

=198.= =Ruby.= This jewel, of a rich, velvetty, red color, exists in

three principal varieties: oriental, spinel and balas rubies, which

differ as regards their chemical composition.

From a jeweler’s point of view, the value of a ruby is enhanced by its

rich color and transparency; but this is not the case in regard to its

application in horology, for which hardness and capability of taking a

high polish are mainly necessary.

The specific gravity of the three varieties is: oriental, 4.2; spinel,

3.7; balas, 3.6.

The first of these is the best, since it is the hardest, both taking

a better polish in the first instance and retaining it for a longer

period.

In comparison with the other varieties, its specific gravity is greater

and it possesses a brighter color, but will often be found to be less

transparent.

Spinel and balas rubies are frequently met with that are very beautiful

to the eye, but their hardness is inferior to that of the sapphire

and even of the chrysolite. They must be carefully excluded from all

good work, for, either in consequence of the inferior hardness or the

mode in which the oxide of iron, magnesia, etc., is combined, or of

other causes, oil rapidly deteriorates in contact with them, and the

moving parts, especially if they are of steel, soon show signs of wear.

The rubies themselves also suffer, and it is by no means uncommon,

especially in the case of the duplex escapement, to meet with such

jewels quite rough and even pitted on their acting surfaces.

=199.= _False ruby._ In a certain class of watches, a variety of stones

pass for rubies that are known to jewelers as rubicelle, rubace, rock

ruby, Brazil, Siberian or Bohemian ruby, rose ruby, etc., the hardness

of which is even less than that of rock crystal. Pivot-holes made of

these imitations of the real ruby are worth less than plain brass

settings.

=200.= =Sapphire.= The color of this stone, sometimes even milky,

passes through all the shades of blue. Like the ruby, there are several

varieties that differ appreciably in regard to hardness. The hardness

of oriental sapphire is equal to that of oriental ruby; both consist of

nearly pure alumina, colored by a little oxide of iron; their chemical

composition thus being the same, they only differ in regard to color.

It is, then, a great mistake on the part of watchmakers to prefer

spinel or balas rubies in place of oriental sapphires.

The sapphire is more brittle than the ruby.

The other kinds of sapphire, such as water sapphires, are not true

sapphires; they are soft and should never be used in horology. The

density of the oriental sapphire is about 4.01, whereas that of other

kinds is only 2.58.

=201.= =Chrysolite.= Under this name lapidaries include a variety of

stones of yellow-green, apple-green with shades of yellow, and other

colors.

That known as oriental chrysolite, which is the same as the oriental

topaz, has a beautiful pale yellow color with shades of apple-green; it

is the most highly esteemed. This stone has a sufficiently high degree

of hardness for use in watchmaking, as it will scratch rock crystal.

Its density varies from 3.73 to 3.00.

The other varieties, ordinary chrysolites, come very low in the scale

of hardness. They can be scratched by quartz, rock crystal and even by

the file, and are thus of no use for watches.

=202.= =Agate, Carnelian, Topaz.= Only the varieties of the stones

already considered that are termed oriental can be used for the

pivot-holes or the pallets of astronomical regulators, but for the

escapements of the ordinary timepieces of commerce, such, for example,

as the pallets of Brocot escapements, the topaz, agate or carnelian

may be used. When of the hardest kind, and capable of receiving a high

polish, they will very efficiently resist the friction of brass teeth.

As to the softer kinds, they are inferior to hardened polished steel

for pallets.

WORKING IN PRECIOUS STONES.

=203.= The methods adopted for working in the precious stones are in

great parts kept secret by those who practise them; it is, however,

well known to watchmakers that jewels are usually worked and polished

with powdered diamond, and the following details will afford all the

information necessary to enable the reader to make a jewel of any

required form. Where not otherwise stated, the information is taken

from a work published by N. Dumontier.[5]

=204.= =Tools for working jewels.= These are all of simple

construction, and can be made by any watchmaker if, indeed, he has not

them already to hand.

[Illustration: _Fig. 47._]

(1.) A small lathe arranged to receive chucks, fixed to the bench or in

a vise, and driven by a foot-wheel. Its form resembles that shown in

fig. 47.

(2.) Two circular laps of copper and one of tin about 2 inches in

diameter and ⅛th inch thick; these present a flat face for grinding,

smoothing and polishing the stones, and are adapted to the nose of the

lathe.

(3.) A small barrel (that also screws into the nose of the lathe) with

six brass covers, perforated at the center, on which to cement the

jewel-holes, when enlarging, smoothing and polishing their holes.

(4.) A flat steel circular cutter half an inch in diameter, for

slitting stones. Also two similar discs, one of copper and the other of

tin, of the same size, and having sharp edges, are occasionally useful.

(5.) Two small laps, one of copper and one of tin, to smooth and polish

cylindrical stones. These laps are mounted in place of the T-rest,

or in the slide-rest, in such a manner that they can be rotated in a

horizontal plane by a bow, in a manner sufficiently indicated by fig.

48.

[Illustration: _Fig. 48._]

(6.) Two chucks adapted to the lathe, on which to cement the jewels for

drilling, turning and polishing.

(7.) A number of small broaches, spindles with concave and convex ends,

etc., for smoothing and polishing jewel-holes, convex and concave

surfaces.

There may also be added a small steel plug mortar for powdering the

diamond (=169=), and a flat steel plate with a block for working up the

powder.

=205.= =Selection of Stones.= This is of the first importance. By

the aid of a powerful lens, or a microscope, ascertain that they

contain no cracks, air cavities or black specks; avoid stones that are

milky, preferring such as are marbled, and in which the directions of

crystalization seem to cross one another, as they are the hardest. The

hardness may be tested by trying them one against the other (=122=),

but an experienced workman needs only to note the amount of resistance

it offers to the operation of cutting on the lap. The density also

affords a valuable means of determining the nature of stones. (See

above notes on the several kinds.)

=206.= =To find the axis of crystallization of a stone.= It is well

known that jewels differ from glass, in that they form crystals of

certain definite forms; they are therefore termed “crystalline,”

whereas glass is “vitreous.” If a jewel-hole is drilled in any

direction other than the axis round which the crystal may be assumed to

have been formed, there will be difficulty experienced in the drilling

and polishing; the edges of the hole will become rough during the act

of rounding them off, and the hardness will appear to be irregular.

This point seems, however, to be ignored by the majority of jewel-hole

makers, although the determination of the most suitable direction

presents no difficulty.

Obtain, from any optician, two tourmaline plates cut parallel to their

axis of crystallization and with their faces polished. Mount them

in a light frame, parallel to each other, so that each can rotate

independently of the other round the axis through their centers; it is

convenient if a light spring tends to bring the plates together so that

a stone can be held when placed between them. Or such an arrangement

can be bought ready made at most opticians: it is known as a tourmaline

polariscope. If this instrument be held up between the eye and a light,

and one plate be rotated while the other remains stationary, it will be

seen that the light becomes gradually greater or less according to the

direction of rotation; and further, if the plates be good ones, a point

will exist at which there is nearly total darkness.

To examine a stone, cut and polish on it two parallel faces

approximately at right angles to the axis of crystallization; this can

generally be roughly guessed at by inspection. Place it between the

plates (when set at their darkest position), and not only will the

light be in part restored but beautiful colored rings will be formed.

If they are circular, the faces of the stone are at right angles to

its axis; if not, incline it till the rings become so, and the axis

will then coincide with that of the instrument. In case the rings are

not observed at all, the stone must again be cut at right angles to

the original direction, and the experiment repeated. If they still do

not appear, the stone is unsuitable for drilling, but may be used for

pallets, locking-stones, ruby-pins, etc.

The stones to be examined in this manner must be larger than those

commonly met with, and if cylindrical rubies can be obtained they are

to be preferred, as it is then only necessary to slice them across

their axis.

It should perhaps be observed that these precautions can only be taken

in making jewel-holes for the higher class of clocks, chronometers and

watches. The cheaper class must of necessity be cut in such a manner as

their figure may suggest.

=207.= =Making jewel-holes.= Having selected 20 or 30 stones of about

the same height, cement them to a smooth brass or copper-plate, heated

to melt the cement. Hold this plate in contact with a revolving copper

lap in which the coarser quality of diamond powder (=169=) has been

embedded by means of a hard steel block; the lap is moistened with

water.

When one side of the stones is true, soften the cement and, after

washing, place them in a vessel containing spirits of wine heated by

a lamp. After doing the same to the plate, again cement the stones to

it with the trued sides downwards, and grind the other faces until

the desired thickness is arrived at. Clean the stones and smooth them

on the brass lap charged in a similar manner with a finer quality of

powder.

The stones are now ready for drilling. This may be done with diamond

powder, or with the diamond drill, both of which methods will be

explained.

=208.= _To drill with powder._ In drilling with powder, the stone is

fixed with sealing-wax or shellac on a carrier that is adapted to the

tool-holder of the slide-rest, this carrier being provided with a

vertical slide, so that by the screws in three directions the stone can

be accurately centered; it is, moreover, so arranged that the stone can

be advanced to or from the drill by pressing with the finger axially.

Drill a small hole in the center of the chuck and, after fixing a piece

of steel in it that has been hardened and tempered to a greyish color,

turn a point on it about twice the length of a pivot, to serve as a

drill. This point must be slightly thinned backwards to prevent it from

choking in the hole and its end should be flat, so as to retain the

powder.

When the stone is exactly centered, place No. 2 diamond powder on the

end of the drill, and press the stone gently against it, constantly

releasing it from the drill for an instant at a time. The hole will

be perforated in from 8 to 15 minutes, according to its depth, during

which interval the powder should be renewed two or three times. Remove

the stone and fix it on the barrel-chuck cover so as to turn true in

the lathe; then turn out the oil-cup with a diamond graver of suitable

form. See again that the stone is central, and re-center it if this be

found necessary. This is done with the smooth conical end of a soft

round broach, or a pegwood, a lamp being held under the chuck at the

same time.

=209.= _To use the diamond drill._ Having centered the stone on the

chuck, as explained in the preceding paragraph, set it in rotation

and bring a sharp-pointed diamond graver against its center, pressing

lightly and resting the handle on the =T=-rest; a minute central mark

is thus made in the stone for maintaining the drill axial. Selecting

a diamond drill of convenient diameter, moisten it in the mouth and

present it to the mark, applying a gentle pressure, the amount of

which can only be ascertained by practice. It is to be observed that a

number of stones should, if possible, be drilled at the same time, for

the hand is apt to lose the requisite knack, if only one or two are

perforated at a time.

=210.= =Smoothing and Polishing.= When the hole is made through,

remove the stone and invert it on the chuck. The diameter being less

than that ultimately required, pass a brass broach charged with No.

3 powder through the hole, giving it a gentle axial motion while the

stone revolves, and taking care to avoid pushing it so far forward as

to lock in the stone, and holding it very lightly between finger and

thumb. When sufficiently smooth, clean with rotten wood or soft bread,

and treat it in a similar manner with a copper broach and No. 4 powder.

Then again clean and use a tin broach and powder No. 5. Next, taking

a small bone cone, smooth the angles of the holes; then use a copper

wire with rounded end for smoothing the oil-cup (with powder No. 3);

follow as explained for the hole with the finer degrees. Using a finely

pointed pegwood that passes through the hole, _marry_ or round off the

internal angle between the hole and oil-cup (the powder that remains

in the hole being sufficient for this purpose) and do the same to the

outer circumference of the cup with a copper spindle of somewhat larger

diameter.

Round off external angles with a diamond graver followed by a copper

polisher, the end of which is cup-shaped. The flat face of the stone is

polished with a small copper disc and No. 4 powder, pressing it lightly

with the finger at the same time that a circular movement is given to

it; finish with No. 5 powder. Or the stone may be detached and the flat

face polished by working on a ground glass plate, a pegwood point being

passed into the hole to form a handle.

Re-set the stone, inverting it, on the chuck, centering it. The other

side is then polished in the same manner, using such tools as its form

may require.

Having thus completed the stone, examine it carefully with a powerful

glass to ascertain that the hole is highly polished and the angles

rounded off, etc. It is then ready for setting.

=211.= =Setting Jewel-holes.= Whether it be a plate, cock or bushing

in which the stone is to be set, the piece must always be cemented

to a chuck and the hole accurately centered. Turn it out to a depth

corresponding to the thickness of stone, and make a circular groove

round the hole thus made with a round-pointed graver, only leaving a

very thin fillet of metal on the inside. The stone should fit easily

in the hole, but without play, and should pass in to such a depth that

its surface is slightly below that of the plate, etc., when there is

an end-stone; in other cases it must, of course, often depend on the

end-shake to be obtained. At the same time it appears desirable that it

always should be slightly below.

Clean out the setting and place a small quantity of oil in it to

prevent the stone from flying out when made to rotate; or it may be

rendered still more safe by a pointed pegwood held in the hand. The

stone is fixed in position with a small conical burnisher (as, for

example, the point of a round broach) very carefully polished, so as

to avoid all abrading action; if an excess of metal is forced over the

surface of the stone, it is removed with a graver. The surface of the

brass is finally smoothed with pith or pegwood, and tripoli in oil,

followed with polishing rouge in spirits of wine.

English jewel-setters often do not turn the groove, but leave a

projecting edge round the hole, which is pressed on to the stone with a

burnisher.

=212.= =To Make End-stones.= The details already given will enable any

intelligent workman to make end-stones. If one of diamond in a brass or

steel setting is required, take a small rose-cut stone, turn out a hole

in the chuck to receive it, and, after cementing in position, turn off

the corners with a diamond graver so as to be able to set it.

For making end-stones of ruby, sapphire or chrysolite, flatten a face,

using the laps Nos. 1, 2, and 3 in succession, or a plate of ground

glass. Then cement with the flat face towards the chuck, and turn to

the requisite form with a diamond graver. Polish with the cup-ended

brass and copper spindles, and set, if requisite, in the same manner as

a jewel-hole.

=213.= =To make pallets, unlocking pallets, etc.= This may be done

on the lap, or by using files of soft steel, copper and tin. In the

first case the stones are roughed out while held by the hand, and the

required form is given them while holding them in a small carrier that

fits into the T-rest support, but the forms of such stones are so

various that no special details can be here given. The diamond powder

of different degrees of fineness is used, as in making jewel-holes.

=214.= =To make semi-cylindrical locking stones, ruby-pins, etc.= The

stone must first be made approximately cylindrical on the lap No. 1,

so that it may be turned with the diamond graver. Drill a hole in the

chuck, cement the stone in it and turn it in this manner. When true

and of the requisite length and diameter, round off the outer end and

smooth with a cup-ended spindle, then polish with powders 3 and 4

successively. Round off the sharp corner with a cup of rather greater

curvature. The cylindrical surface is polished by means of a small lap

carried on a vertical spindle in a frame fixed in the T-rest support,

and caused to rotate rapidly with a bow, the lathe-head also revolving

at the same time (=179=). The lap-carriage should have a vertical screw

adjustment so that it may be brought just into contact with the stone;

it is supplied with the several degrees of powder in turn. Now drill

a hole in another chuck of the diameter of this cylinder, fix it in

position and finish off the opposite end.

To form the flat face along the axis of the stone it is cemented to a

support in place of the =T=-rest and brought against the revolving lap

in the lathe; or the same result may be attained by using a brass file.

=215.= =To make a duplex roller.= At the present day this operation

so rarely has to be done that only a few words can be devoted to its

consideration.

Very pure rubies must be selected, and the hole drilled as explained

in =209=; if the drill is too short it must be introduced at opposite

ends, and the two holes made to meet. After smoothing the surface, the

notch is cut with the thin steel cutter referred to in article =204=,

the roller being cemented to a support that replaces the T-rest. When

the steel disc charged with powder No. 4 is revolving very rapidly,

advance the roller under it by a screw. The notch is polished by a

small copper file of suitable form, and its corners rounded off by a

tin one of square section, one edge of which enters the notch.

=216.= =To mount diamond drills and gravers.= Drill a hole or file

a notch in the end of a piece of brass wire to correspond with the

fragment of diamond; heat the end in a spirit lamp and lay on it a

piece of good sealing-wax or shellac. When this commences to melt, set

the diamond in position and leave the whole to cool. Diamond drills are

very commonly mounted at the end of a pin that has had its point filed

off; mark a point on the end with a graver and drill the hole, which

should be very shallow. Holding the pin in a pin-vise with its point

projecting about 1-10th inch, heat the vise in a lamp, and proceed as

above explained.

FOOTNOTES:

[4] The theoretical density of an alloy, on the assumption that in

alloying the metals do not contract or expand, is obtained by dividing

the percentage proportion of each constituent metal by its density,

adding the products so obtained together, and dividing their sum into

100.

[5] _L’art de travailler les Pierres precieuses a l’usage de

l’Horlogerie et de l’Optique._ Paris. 1843.