156 ANNUAL OF SCIENTIFIC DISCOVERY. 



moistmv softens the parts exposed to the light, so that Avhcn charcoal, or any 

 other >ubstance in impalpable powder, is sifted over the picture, it adheres to 

 the softened parts of the picture. By the same process enamels may bepro- 

 dmvd dhvrt from the camera, or otherwise, by sifting a metallic oxide over 

 the gelatine on the enamel plate, and then heating in the furnace. 



Application of Photography in construction of Micrometers. The successful 

 application of photography in the construction of micrometers has been 

 made by Mr. Clarence Morfit, of the United States Assay Office, New York. 

 It is merely the reduction of a large scale of exact dimensions and divisions 

 to a definite size, suitable for microscopic instruments. A scale of ten inches 

 divided into inches and tenths of an inch has been reduced in this manner to 

 one-twentieth of an inch, thus making its smallest divisions equal to one 

 two-thousandth part of an inch square. The method is simple, accurate, and 

 economical. Moreover, the micrometer has the advantage of giving the 

 exact measurement of the object in fractions of an inch, and at the same time 

 determines the power of the microscope itself. Silliman's Journal. 



Adaptation of Machinery to Photography. At a meeting of the American 

 Fhotographical Society, Aug. I860, Mr. G. H. Babcock called attention to a 

 plan devised by Mr. Charles Fontayne, of Cincinnati, Ohio, for the adapta- 

 tion of machinery to photographic printing. The general plan adopted was 

 given as follows : 



A negative is fixed in a box, together with a sheet of prepared paper, and 

 the latter exposed by automatic machinery to the condensed light of the sun 

 passing through the negative. After each exposure the paper is traversed 

 underneath the negative, to present a fresh surface for the succeeding impres- 

 sion. These motions, together with that of clamping the negative into close 

 contact with the paper at the instant of exposure, are all performed by the 

 operator simply turning a crank. 



The rapidity of the process, as witnessed by Mr. Babcock, was stated to 

 be at the rate of two hundred impressions per minute: the photographic 

 paper used is prepared by a process known only to the inventor. 



If this invention is what it is represented to be, it opens a field for pho- 

 tography hitherto impracticable, in consequence of the time and expense of 

 printing, as ordinarily practised. The illustrations for a book, having all the 

 exquisite beauty and perfection of the photograph, may be turned out, by the 

 use of this machine, with a rapidity wholly undreamed of, either in plate 

 printing or litWbgraphy. The expense of engraving may be dispensed with, 

 and the negative come direct from the artist's hands, drawn upon a prepared 

 glass, from which, in the course of a few hours, the plates for a large edition 

 may be printed, each one a perfect duplicate of the original drawing. 



NEW METHOD OF COPYING ENGRAVINGS. 



The London Builder gives the following rule for transferring engravings 

 to white paper: Place the engravings for a few seconds over the vapor of 

 io-linc. Dip a slip of white paper in a weak solution of starch, and, when dry, 

 in a weak solution of oil of vitriol. When dry, lay a slip upon the engraving, 

 and place them for a few minutes under the press. The engraving will thus 

 be reproduced in all its delicacy and finish. The iodine has the property of 

 fixing the black parts of the ink upon the engraving, and not on the white. 

 This important discovery is yet in its infancy. 



