been shown by Chevreul to be an impossibility. No substance is known
that does not possess the power of reflecting light to some extent.
If paper is blackened, its surface will reflect rays that can act
powerfully upon the sensitive plate in a camera, even if the eye, by
convention and association, would determine it to be actually black.
The same is to be said of black silk and velvet. The latter, more than
any other substance, approaches real black. It is an object of common
observation that all colors show much more strongly in velvet than in
any other material. The reason for this is that, owing to the depth of
the pile, the light undergoes multiple reflection. The percentage of
white light is diminished with each reflection, and the colored rays
become less and less contaminated with those of other hues. The same
reasoning applies to black velvet. The light by multiple reflection
from its substance is more and more absorbed, and the familiar intense
black is the result. A piece of this material, placed upon cloth or
silk, always appears, and is, the blacker. In choosing velvet for such
experiments, care must be taken not to use a blue black. The dead black
is the proper one to select.
[Illustration: CHEVREUL'S BLACK.]
Black being the absence of color is producible by excluding light. The
production of the velvet black, we have seen, depends on the mechanical
texture of the goods. Nothing is so black as a perfectly dark room.
Carrying out these principles, Chevreul devised the wonderfully
ingenious way of producing a true black which we illustrate.
He lined the interior of a box with black. Pigment, black silk, or
black velvet may be used. In the cover of the box he made a hole, not
too large, but bearing a certain ratio to the area of the cover. The
size should not exceed one-tenth this surface. The spot thus produced
reflected no light, as there was no surface. The interior of the box,
by color and shadow, was prevented from reflecting any light, so
that absolute blackness resulted. The blackest velvet or silk placed
alongside of this spot appears lighter in color.
In constructing the apparatus illustrated, a famous proverb was
selected as a theme, in which a certain personage is stated not to be
so black as he is painted. The author of "English as She is Spoke"
renders this proverb, "He not so devil as he is black." The blackness
of this image is absolute.
A pasteboard box is lined with black silk or velvet, and any desired
figure is cut through the cover. This may then be painted as black as
possible, or before the figure is cut out, silk or velvet may be pasted
over it, and the figure cut through pasteboard and covering together.
Then, on putting the cover in place, holding the box so that a side
light will fall upon it, thus preventing direct access of light rays
to the interior, the figure will stand out strongly black against a
background which, but for the contrast, would itself be pronounced
absolutely black.
To apply the most rigorous test, a member of the Society of Amateur
Photographers of New York made a photograph of such a box. A carbon B
dry plate was used, with thirty-five minutes' exposure, with stop f-30.
The result was a negative perfectly transparent where the figure came,
but strongly affected by the black box cover. Part of the cover was
coated with black silk and part was painted, but both reflected light
enough to produce a full photograph upon the plate.
A most interesting application of this principle on the large scale has
been made of late years, especially by E. J. Marey, in the photography
of moving animals.[2] With Chevreul's black as a screen, a plate can be
exposed unaffected by the background, and will reproduce objects moving
across the space with perfect fidelity.
[2] See SCIENTIFIC AMERICAN SUPPLEMENT, Nos. 579 and 580, for fully
illustrated article on this subject.
The American Exhibition, London.
Recently we had an opportunity of going over the grounds of the
forthcoming American Exhibition at Earls Court. The site is comprised
in the triangle between Earls Court, West Brompton, and West Kensington
stations, and is thus extremely well situated for easy access from all
parts of London. The area that will be covered by the exhibition is
about twenty-three acres, eight of which are on one and fifteen on the
other side of the West London line, an iron bridge over the railway
connecting the two portions. Although the work has been going on for
some time, little is as yet seen of any building, the operations up
to the present having been confined mostly to earth works, leveling,
and draining. The land to be occupied by the exhibition might almost
be called virgin soil, and all the drains had to be put in by the
company. A good deal of soil has been moved, and some artificial mounds
of considerable extent have been thrown up. In that portion of the
exhibition which will be illustrative of the "Wild West," a large arena
and a grand stand capable of seating 25,000 persons are in course of
construction. The feature of special interest to engineers is, however,
on the other side of the grounds, where the main building for the
reception of the machinery and other exhibits is now being erected.
The main hall has a frontage of brickwork 240 feet long, but the rest
will all be constructed of iron and glass. The total length of this
hall is 1,200 feet, and a special feature in its construction is the
employment of old steel rails for the columns, purlins, and rafters,
on a plan devised by Mr. H. G. Wynne, the engineer to the company. The
whole of the framework is thus made out of old rails, the only portions
specially made for the purpose being the cast iron sockets for the
columns, cast steel shoes for the connections between purlins, rafters,
and columns, and tie bars, which are made of ordinary round iron.
There will be six bays of 30 feet each, and one bay of 60 feet. The
columns are formed by two rails, riveted together with their flanges,
so as to present a cross in transverse section. These are placed into
cast iron sockets, which are set upon cement piers sunk in the ground.
The outermost columns for the first and last spans are provided with
struts, also formed out of rails, fixed to a sleeper, connecting
the bottom of the strut with the foot of the column, this provision
being made to provide against lateral strains; but the columns of the
intermediate spans have no struts. The rafters are also made of rails,
placed with the flanges uppermost, those for the short spans being in
one length, but those for the long spans being fastened together by
fish plates. The usual length of rail employed for the columns is 18
feet and 24 feet. There is a fall in the ground of about 2 feet to
both sides from the middle of the building. To avoid the necessity
of employing columns of different lengths, the ridge of the roof is
carried parallel to the ground, and will therefore also show a fall
of 2 feet on each side of the middle. This will be hidden by a loose
louver, which is placed all along the ridge, so that the outline of the
roof will appear straight and horizontal. The sides of the building
will be of galvanized corrugated iron.--_Industries_.
* * * * *
PETROLEUM IN EGYPT.--At Jemsah, in Egypt, in boring for
petroleum, ozokerite, or solid petroleum, has been found at a depth of
365 feet, and 15 feet lower a close grained coral has been struck. At
another boring, slight traces of gas and oil have also been found.
ENGINEERING INVENTIONS.
A spark arrester has been patented by Mr. John C. Albrecht, of
Columbus, Ga. Combined with a draught pipe is a cone with curved
volutes, and in its center and underneath it an inverted cone, with
spark pockets, and other novel features, the sparks being returned to
the fire box, the invention being an improvement on two former patented
inventions of the same inventor.
A steam condenser has been patented by Mr. John McIntyre, of New York
City. It is cylindrical in form, a central perforated or slotted casing
being used in connection with the cooling pipes, with a regulating
valve to open or close the perforations or slots, in such way that the
cooling effect will be more instant and the temperature of the cooling
parts more equal than in ordinary condensers.
A car coupling has been patented by Mr. George W. Giles, of Buffalo,
West Va. In connection with a suitable drawhead, a weight and pin
are joined by a flexible connection, the weight being adapted to
overbalance the pin, and the weight being projected into the path of
the drawbar, so that the entering drawbar will raise the weight, and
thus permit the pin to fall by its own gravity into coupled position.
A car coupling has been patented by Mr. Wesley E. Roberts, of Hartford,
Ky. The coupling link consists of a straight bar, with a wedge shaped
pointed lug at each end, a spring being fastened to the under side,
and the coupling being effected by an arm dropping in front of the
lug after the link enters the drawhead, the device being simple in
construction, and one which can be operated from the side or top of the
car.
AGRICULTURAL INVENTIONS.
A mower has been patented by Messrs. James B. Nieth and Charles
L. Thomas, of Independence, Iowa. This invention covers a novel
construction and combination of various parts of the machine, so that
it will operate with less friction than ordinary mowers, while being
simple in construction and not liable to get out of order.
A plow has been patented by Mr. Thomas J. Eriom, of Union Church,
Miss. It is an improved garden plow, with simple means for adjusting
the gauge wheel to regulate the depth of working, and a breast bar for
pressure by the operator to increase the propelling power and to give
the plowman a better control of the plow, with other novel features.
MISCELLANEOUS INVENTIONS.
An attachment for elevator doors has been patented by Mr. Edward P.
Walker, of Kansas City, Mo. It is an attachment designed to effect by
the movement of the elevator car the automatic operation of the doors
of the shafts, so that the elevator man is relieved of this duty.
A saw gummer has been patented by Mr. Eli Rogers, of Fulton County,
Ind. The invention consists of a cam lever operating a spring arm on
which is pivoted a tool holder, making a device which is simple in
construction, durable, and effective in operation.
A hame has been patented by Mr. John E. James, of Mossy Creek, Va. It
is so made that the shoulder of the horse will not be affected by heavy
jars, and the hames may not only be fitted to any length of collar,
but the point of draught may be shifted, so that the draught will be
brought to the proper point.
A tongue support has been patented by Messrs. Charles W. Van de Mark
and Calvin Moore, of Clyde, Kansas. The construction is such that the
tongue may be supported so as to relieve the team of its weight, and
the devices for supporting it are simple, inexpensive, and not likely
to get out of order.
A fence post has been patented by Mr. John J. Kimball, of Naperville,
Ill. Combined with side strips are rivets, spacing strips arranged
between the side strips, clips formed with apertures, and staples
arranged to pass through the apertures, making a cheap, durable, and
efficient post for barbed wire fences.
A combined chair and lounge has been patented by Mr. Gustavus Hamel, of
De Soto, Mo. The parts are so arranged that the back of the chair may
be adjusted to any angle desired, and the attachment constituting the
foot rest or foot of the lounge may be disposed beneath the main seat
of the chair when not in use.
A harmonic keyboard for violins has been patented by Mr. James F.
Poage, of La Plata, Mo. It is designed to enable the performer to
produce harmonic high tones without great difficulty, and is attached
to the neck of violins of the usual construction, the keyboard being a
combination of pivoted finger keys with a pivoted stop plate.
A rein holder has been patented by Mr. William Tennison, of Mount
Vernon, Ind. This invention covers an improvement in rein holders
consisting of a skeleton frame adapted for attachment to a harness or
for support upon a horse's back, and used for the purpose of supporting
the reins out of the way of the animal's tail.
A collar button has been patented by Mr. Leopold Baer, of San
Francisco, Cal. To the center of the button back is secured a tubular
shank in which is a spiral spring, there being a knuckle joint by which
a tongue may be held in three different positions, the device making a
conveniently working button for holding the necktie in place.
A bridle has been patented by Mr. Benjamin S. Seaman, of Corning, N.
Y. The cheek plate is formed with studs on which the blind sheet is
adapted to be placed, and secured by a key plate constructed to engage
with the studs, the cheek loop being secured to the cheek plate with
the same stud plate and key plate which hold the blind.
A machine for bending carriage thills has been patented by Mr. Thomas
E. Montague, of West Lorne, Ont., Canada. It is for bending wooden
shafts or thills for buggies, sulkies, carriages, and other vehicles,
and covers a novel construction and combination of parts and details,
whereby thills of greater or less thickness can be bent, the machine
operating very rapidly and automatically.
A nut lock has been patented by Mr. Jeremiah C. Butler, of Lexington,
Mo. The construction is such that the key may be drawn off the bolt by
the nut, and need not be bent out straight into the keyway of the bolt
to prevent its locking portion engaging in the recesses of the nut as
the latter is being turned off the bolt, the key needing only to be
bent very slightly for adjustment into locked or unlocked position.
A trousers stretcher has been patented by Mr. Charles E. Ray, of San
Francisco, Cal. The trousers are clamped below the waist band and at
the bottom, the clamp at the waist band attached to a spiral or rubber
spring, secured in fixed position at one end, while to the clamp at
the bottom is attached a strap by which tension can be placed upon the
trousers, and permanently maintained.
A log dog has been patented by Mr. Eugene H. Allman, of Mobile, Ala. It
is made of heavy wrought iron, with a flat body portion, and having end
points or fangs, and is applied to the chain by shouldered clips, all
extra chains and dogs being dispensed with by its use, and when used on
endless chains it being only necessary to point the logs in the logway,
when the dogs take hold and bring them up.
An electrical weighing scale has been patented by Mr. Willis M. Hunt,
of Glen Gardner, N. J. Combined with feeding hoppers arranged above the
scale pan are valves operated by connection with the foot lever for
discharging the hoppers, and combined therewith is an electro-magnetic
holding and releasing device, which automatically stops the feed when
the scale beam is tipped.
A boot or shoe stretcher has been patented by Mr. Lloyd Nottingham, of
Norfolk, Va. Centrally pivoted levers have apertures in their lower end
to receive pins with rounded outer ends, and above the pivotal point
is an adjusting screw to separate the levers in stretching the boot or
shoe, the levers being held apart by locking pieces, the device being
simple, strong, and easily operated.
A combined bench and ironing table has been patented by Mr. Daniel
H. Weller, of Boyertown, Pa. Combined with a reversible board with
covered socket boxes are supports hinged to the legs of a bench, with
other details, to make a desirable piece of furniture to serve the two
purposes of a seat and a table to iron upon, with compartments for
keeping the cloths used in ironing.
A window frame and sash has been patented by Mr. John E. Jones, of New
York City. The construction is such that the sashes when closed are to
all intents and purposes air tight, and wear and friction are removed
from the packing strips, so the sashes may be raised and lowered
without injury to the packing, the invention being an improvement on a
former patented invention of the same inventor.
A tug fastener has been patented by Mr. Daniel T. Chambers, of
Mansfield, Ohio. It is in the nature of a divided button, one portion
integral with a shank that goes in the end of the single tree, and the
other formed of two limbs, one completing the periphery of the button
and the other extending up parallel with the shank and forming a part
of the neck beside the button on which the trace is contained.
A tug fastener for single trees has also been patented by the above
inventor. It consists of a tilting latch hinged upon a horizontal axis
at or near the end of the single tree, with one hub adapted to lie
longitudinally with the single tree and the other to project upwardly
at about a right angle thereto, making an easily operated device for
fastening the traces to a single tree.
A plaster fastener has been patented by Messrs. Forest M. Lampson,
Alpheus M. Laning, and George W. Hogben, of Ripon, Wis. It consists
of a metallic washer formed of thin sheet metal, slightly convex,
and provided with a countersink in the center, formed by the process
of stamping, the device being intended to secure plastering loosened
by shrinking of the lath, etc., before it becomes cracked and
disintegrated.
A combined towel, hat and paper rack has been patented by Mr. Elbridge
L. Scribner, of Amesbury, Mass. (P. O. Box 98). It is a simple,
inexpensive, and efficient device, consisting of a frame formed of end
pieces of wood, connected by wooden slats on the back, and supporting
three rods of metal or wood for receiving the articles to be held, the
lower rod being designed for receiving a roller towel, and the upper
rod being offset or cranked for convenience in placing articles on the
lower rods.
NEW BOOKS AND PUBLICATIONS.
MINERAL RESOURCES OF THE UNITED STATES, CALENDAR YEAR 1885.
Washington: Government Printing Office, 1886. Pp. 576.
This is a carefully compiled volume, giving the statistics for mineral
products in the United States. Coal, coke, petroleum, and natural gas
are first treated of; the metals, from iron to zirconium, come next.
Under aluminum the work of Col. Frishmuth, of Philadelphia, and of
the Cowles Smelting Company, of Cleveland, are noted. In view of the
demand for zirconium pencils for the oxyhydrogen light, the section
on the sources and preparation of the oxide, by Mr. David T. Ray, is
of special interest. Other subjects treated are structural materials,
abrasive materials (buhr stones, etc.), precious stones, fertilizers,
glass materials, and, under many other headings, a complete review of
the titular subject appears. We also note a section of much interest on
mineral paints, by Mr. Marcus Benjamin, F.C.S. In it the preparation
of barytes as an adulterant for paints is described at some length.
In some instances an elaborate explanation of the classification of
paints as adopted is given. In other cases it is entirely omitted. The
first system is certainly preferable. A very full index closes the
work. It can be had on application to the Director of the United States
Geological Survey, Washington, D. C., the cost of printing and binding
(40 cents) being at the same time remitted.
Business and Personal.
_The charge for Insertion under this head is One Dollar a line
for each insertion; about eight words to a line. Advertisements
must be received at publication office as early as Thursday
morning to appear in next issue._
Best tempering fluid known--Mercury, potash, and hydrochloral. $2.00
per gallon. Samples, 25c. Address Chemical Works, New Albany, Ind.
Hodges' universal angle union makes pipe connection at any angle.
Rollstone Machine Co., Fitchburg, Mass.
To makers of water wheels, current wheels, and horizontal
turbines--Please address W. H. Garlick, Calumet, Ohio.
Sphero! A new and original game; an out-door sport; unlike any other.
Apparatus of wood, simple, inexpensive. Packed like croquet, and cost
to manufacture about the same. Patent pending. Rights, etc. Address J.
M. Hughes, Brooklyn P. O., N. Y.
The H. W. Johns Manufacturing Co., 87 Maiden Lane, N. Y., will send
to any address in the United States, postage prepaid, a trial package
of ¼ pound of asbestos wick packing and 1½ pounds of asbestos piston
rod packing, on receipt of one dollar; or ¼ pound of asbestos wick
packing and 3½ pounds of asbestos piston rod packing, on receipt of two
dollars. Give address in full--name, town or city, county, and State.
The H. W. Johns asbestos packings are the best and most economical made.
For Sale--Ivory button works. Large, well lighted building; 20 H.P.
engine; capacity, 200 gross per day; doing splendid business; plenty of
cheap labor. Price, only $3,000. Address T. Bergy, Caledonia, Mich.
Wanted--A pushing man, capable of taking charge of a shop for
building engines. A fine chance for a skilled mechanic. Address, with
references, etc., lock box 17, York, Pa.
Blake's Improved Belt Studs are the best fastening for Leather and
Rubber Belting. Greene, Tweed & Co., 83 Chambers St., New York.
Wanted--Tool agents in shops. Outfit free. E. H. Randall & Co., 154
Lake St., Chicago, Ill.
_Link Belting_ and Wheels. Link Belt M. Co., Chicago.
The _Railroad Gazette_, handsomely illustrated, published weekly, at
73 Broadway, New York. Specimen copies free. Send for catalogue of
railroad books.
_Protection for Watches._
Anti-magnetic shields--an absolute protection from all electric
and magnetic influences. Can be applied to any watch. Experimental
exhibition and explanation at "Anti-Magnetic Shield & Watch Case Co.,"
18 John St., New York. F. S. Giles, Agt., or Giles Bro. & Co., Chicago,
where full assortment of Anti-Magnetic Watches can be had. Send for
full descriptive circular.
Woodworking Machinery of all kinds. The Bentel & Margedant Co., 116
Fourth St., Hamilton, O.
Guild & Garrison's Steam Pump Works, Brooklyn, N. Y. Pumps for liquids,
air, and gases. New catalogue now ready.
Concrete patents for sale. E. L. Ransome, S. F., Cal.
The Knowles Steam Pump Works, 44 Washington St., Boston, and 93 Liberty
St., New York, have just issued a new catalogue, in which are many
new and improved forms of Pumping Machinery of the single and duplex,
steam and power type. This catalogue will be mailed free of charge on
application.
Presses & Dies. Ferracute Mach. Co., Bridgeton, N. J.
Nickel Plating.--Sole manufacturers cast nickel anodes, pure nickel
salts, polishing compositions, etc. $100 "_Little Wonder_." A perfect
Electro Plating Machine. Sole manufacturers of the new Dip Lacquer
Kristaline. Complete outfit for plating, etc. Hanson, Van Winkle & Co.,
Newark, N. J., and 92 and 94 Liberty St., New York.
Iron Planer, Lathe, Drill, and other machine tools of modern design.
New Haven Mfg. Co., New Haven, Conn.
Supplement Catalogue.--Persons in pursuit of information of any special
engineering, mechanical, or scientific subject, can have catalogue of
contents of the SCIENTIFIC AMERICAN SUPPLEMENT sent to them
free. The SUPPLEMENT contains lengthy articles embracing the
whole range of engineering, mechanics, and physical science. Address
Munn & Co., Publishers, New York.
Planing and Matching Machines. All kinds Wood Working Machinery. C. B.
Rogers & Co., Norwich, Conn.
Billings' Drop Forged Steel C Clamps. Drop Forgings, all kinds.
Billings & Spencer Co., Hartford, Conn.
Curtis Pressure Regulator and Steam Trap. See p. 45.
Chucks--over 100 different kinds and sizes in stock. Specials made to
order. Cushman Chuck Co., Hartford, Ct.
The Improved Hydraulic Jacks, Punches, and Tube Expanders. R. Dudgeon,
24 Columbia St., New York.
Hoisting Engines, Friction Clutch Pulleys, Cut-off Couplings. D.
Frisbie & Co., 112 Liberty St., New York.
If an invention has not been patented in the United States for more
than one year, it may still be patented in Canada. Cost for Canadian
patent, $40. Various other foreign patents may also be obtained. For
instructions address Munn & Co., SCIENTIFIC AMERICAN patent
agency, 361 Broadway, New York.
Veneer Machines, with latest improvements. Farrel Fdry. Mach. Co.,
Ansonia, Conn. Send for circular.
Tight and Slack Barrel Machinery a specialty. John Greenwood & Co.,
Rochester, N. Y. See illus. adv., p. 28.