The Practical Astronomer: Comprising illustrations of light and colours--practical descriptions of all kinds of telescopes--the use of the equatorial-transit--circular, and other astronomical instruments, a particular account of the Earl of Rosse's large telescopes, and other topics connected with astronomyDick, Thomas
Science
The Practical Astronomer: Comprising illustrations of light and colours--practical descriptions of all kinds of telescopes--the use of the equatorial-transit--circular, and other astronomical instruments, a particular account of the Earl of Rosse's large telescopes, and other topics connected with astronomy
Dick, Thomas
Astronomical instruments; Astronomy; Telescopes
The paper is to be dipped into a solution of salt in water, in the
proportion of half an ounce of salt to half a pint of water. Let
the superfluous moisture drain off, and then, laying the paper upon
a clean cloth, _dab_ it gently with a napkin, so as to prevent the
salt collecting in one spot more than another. The paper is then to
be pinned down by two of its corners on a drawing board, by means
of common pins, and one side washed or wetted with the Photogenic
fluid, using the brush prepared for that purpose, and taking care to
distribute it equally. Next dry the paper as rapidly as you can at
the fire, and it will be fit for use for most purposes. If, when the
paper is exposed to the sun’s rays, it should assume an irregular tint,
a very thin extra wash of the fluid will render the colour uniform,
and at the same time somewhat darker. Should it be required to make a
more sensitive description of paper, after the first application of
the fluid, the solution of salt should be applied, and the paper dried
at the fire. Apply a second wash of the fluid, and dry it at the fire
again: employ the salt a third time, dry it,--and one application more
of the fluid will, when dried, have made the paper extremely sensitive.
When slips of such papers, differently prepared, are exposed to the
action of day light, those which are soonest affected by the light, by
becoming dark, are the best prepared.
When photogenic drawings are finished in a perfect way, the designs
then taken on the plate or paper are exceedingly beautiful and
correct, and will bear to be inspected with a considerable magnifying
power, so that the most minute portions of the objects delineated may
be distinctly perceived. We have seen portraits, finished in this way
by a London artist, with an accuracy which the best miniature painter
could never attempt--every feature being so distinct, as to bear being
viewed with a deep magnifier. And in landscapes and buildings, such
is the delicacy and accuracy of such representations, that the marks
of the chisel and the crevices in the stones may frequently be seen
by applying a magnifying lens to the picture; so that we may justly
exclaim, in the words of the Poet: ‘Who can paint like nature!.’ That
LIGHT--which is the first-born of Deity, which pervades all
space, and illuminates all worlds--in the twinkling of an eye, and with
an accuracy which no art can imitate, depicts every object in its exact
form and proportions, superior to every thing that human genius can
produce.
Reviews
Reviews
No reviews yet
Be the first to share your thoughts on this work.
Elsewhere in the archive
Join the Discussion
Join the discussion
Sign in to leave a comment or review.
Sign InorCreate an account