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☞ _Correspondents should never write on both sides of the paper._
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JAMES TULLEY.—Received. In our next.
GEO. DANIEL.—Professor Wheatstone was the inventor of the reflecting
stereoscope. An account of his invention was published in 1838 in the
_Philosophical Transactions_.
H. W.—The _carte_ enclosed is a very pretty one, both in respect of the
subject and the treatment. Had the oval been omitted and the dome
alone used the effect would have been better.
PHOTO.—Let the south side of the studio be glazed—not with clear but
with ground glass. Should this not be procurable in your town, use
plain glass, and dab it over with putty.
CRAWDON.—India-rubber finger-stalls will prove an effectual means of
keeping fingers clean. We do not use them ourselves; but we know
several gentlemen who do. They cost about threepence each.
EAST ANGLICAN.—There is no remedy for the spots in the paper except more
care in the selection. The spots are owing to minute particles of
metal introduced into the paper when in a state of pulp.
T. M. (Newcastle-on-Tyne).—So far as we know, the only house in the
photographic trade from which you can obtain what is wanted is that of
Mr. F. W. Hart, 8, Kingsland-green. The other matter shall receive
attention.
W. W.—1. A vessel made of gutta-percha will both destroy and eventually
be destroyed by a solution of nitrate of silver.—2. Slate does not
appear to affect a nitrate bath.—3. Bees’ wax is not decomposed by
this solution.
PIETRO CONSTANTINO REMONDINI (Genoa).—Enclosure received with thanks.
The ALMANAC was posted on the 22nd January.
G. W. H.—It is quite impossible from such slender data us that supplied
by you to obtain the information desired, but from the nature of the
subject we are strongly of opinion that it would be dangerous for you
to follow out your proposed intention.
INQUISITIVE READER.—You are mistaken in your supposition concerning the
author of the article. He is not an amateur, but a professional of
high standing, who, for certain reasons, prefers the adoption of a
_nom de plume_ to giving his own name.
INQUIRER.—We could not in this column give you a proper idea of
polarised light. The “three words” into which you would like the
information compressed would have to be extended to many more before
we gave you or our readers a clear idea of the nature and properties
of polarised light.
PHOTOLITHO.—We are aware that Mr. Woodbury has so altered his process as
to get rid of the necessity for using a preliminary coating of
collodion. He now prints on the bare gelatine, and after exposure
mounts the film, sensitive side downwards, on a plate of glass coated
with gelatine and chrome alum.
PORTRAITS BY THE MAGNESIUM LIGHT.—Mr. W. G. Lewis has sent us some
_carte_ portraits taken at night by the magnesium light, which show
that in his hands this neglected branch of photography is very
successfully managed. The faces are full of delicate half-tone. The
time of exposure was three times that required in ordinary daylight.
GEORGE THOMPSON.—1. Although we do not esteem the maker of your lens as
one of the best, he has, for all that, a fair reputation in his own
country; and we know that he has made some good lenses. We have not,
however, heard of him for several years past.—2. Dr. Monckhoven is a
dealer in apparatus—not a manufacturer of lenses.
F. C. S.—Ideas often run in parallel grooves. For several weeks past we
have been using our note-book very freely in the collection of
materials for such a series of articles as that suggested by you. Some
of the information required to render the series of the greatest
possible value is only procurable with much difficulty and at no
little expense; still, such progress in the compilation has been made
as will warrant the indulgence of a hope that we may be able to
introduce the subject at no distant date.
ERRATUM.—In Mr. Coote’s article in our last number, page 38, second
column, eleventh line from top, for “you are apt to hurry and _free_
the development,” _read_ “FORCE the development.” Mr. Coote also
informs us that in the middle paragraph of the first column in the
same page, a sentence there in which he gave his reason for
discontinuing the use of the salt bath for washing the plates will
read better and more correctly as follows:—“Firstly: I found the extra
salt bath and long washing required after it to considerably lengthen
an already sufficiently tedious method of preparation.”
SUBSCRIBER.—Excuse plain speaking, but your pictures are by no means
good—in fact, they are _very_ bad. We are at a loss as to what to
attribute their special qualities—whether to want of care or want of
knowledge and experience. Carelessness, to all appearance, has had
much to do with the matter; for the plate has been badly coated and is
torn, and the developer has not flowed smoothly over the surface.
After you have acquired some more experience and dexterity in
manipulation write again, enclosing a specimen. You need not entertain
any fear of your name and address being divulged.
W. K.—No more easy and expeditious method of collecting oxygen in a bag
can be adopted than that which has so often been described in our
Almanacs and Journals, viz., connecting the bag with the washing
bottle by means of an india-rubber tube, the bottle being in turn
connected with the retort in which the oxygen is generated. The method
of making oxygen from chlorate of potash and black oxide of manganese
is the simplest, cheapest, and best to adopt when only a small
quantity is required. By a small quantity we here mean such a quantity
as will be required by a professional enlarger of photographs in full
practice.
SAM WELLER says—“1. Can you inform me what the method is for enlarging
designs for calico or zinc plates to be engraved for the purpose of
tracing from by pentagraph?—2. Also as to the manner of building a
suitable glass house, and kind of light—north or south?—3. Also, if a
cheap condenser for the solar camera may be made by cementing a clock
glass to a plate of sheet glass and filling it with water?”——We
reply:—1. A design can be placed upon a zinc plate by the combination
of enlarging and photolithography, or by transferring a carbon
enlargement.—2. A north light is better than a south; for the rest, it
will be necessary to consult an architect.—3. This query is answered
with some degree of minuteness in the first paragraph of page 30 of
our ALMANAC for the present year.
OLD HARRY asks—“What is a pistolgram?” We are to some extent ashamed of
the definition we are about to give, but we can offer no other. It is
a small picture taken by a _pistolgraph_, and this, in turn, is a
small camera introduced by Mr. Thomas Skaife, by which photographs
might be taken with a very rapid exposure. We strongly suspect that
“Old Harry” knows more of the subject than he wishes us to believe,
otherwise why put the question concerning the greater angularity of
aperture that is possible to be obtained with a short than with a
long-focus lens? and to which we reply that, without at present
speculating on the cause, the effect is just as he states it to be.
The same principle applies to the object-glasses of microscopes, and
it is an important element in the recognition of object-glasses of the
highest quality.
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