PI!OTO(!KAIMIY, IJKCKXT PRO*. 



721 



. An important advance in the manu- 

 facture of h-nsi-s has resulted from the recent 

 adoption of .Iriui glass by Carl Xfjss, who has 

 obtained objectives entirofy free from spin-Heal 

 nlierrntion and astiginati-m. Another interest- 

 ing inoveiin-nt i> made liy hailmeyer in tho pro- 

 luetii>n of a telephotographies lens for giving 

 enlarged images of distant olijeets. Knlargcd 

 3 have hitherto been produced by long- 

 lenses, or by placing a secondary magni- 

 fier behind the plane of the primary imau'o. Tho 

 new lens is composed of two elements, and the 

 Image formed by it is primary and inverted. Tho 

 anterior element is a positive lens of largo apert- 

 ure and short focus; the posterior lens is a neg- 

 ative element of a fractional part of the focal 

 length of t he anterior positive; and in estimat- 

 ing the rapidity or intensity, the shorter the fo- 

 cus of the posterior lens as compared with that 

 of the anterior lens the greater is the size of the 

 image f<T a given extension of the camera. The 

 main object of the invention is to throw tho 

 nodal point from which the focus is actually 

 measured to any desired distance into a space in 

 front of the lens itself, thus attaining a large im- 

 au r >- without tho aid of a bulky apparatus. The 

 lei;s is said to possess wide adjustability, and to 

 promise important results in astronomical pho- 

 tography. A new (iiindlach lens is on tho basis 

 of Steinheil's double meniscus, which has been 

 transformed into a triple meniscus. A flint-glass 

 lens is inclosed and protected by crown-glass 

 lenses, ground so thin as to minimize the possi- 

 bility of a yellow tinge. English lens makers 

 have urged an agreement on some uniform plan 

 for the threads and flanges of lens mounts. 



Cameras. Improvements in cameras have 

 boon generally in tho direction of greater light- 

 ness for field work, the substitution of cams and 

 ot her devices for screws, etc.. to facilitate rapid 

 adjustment, and the development of the swing- 

 back and reversing features. The most striking 

 advance has been in the devising of hand cam- 

 eras. Cameras that might be operated without a 

 solid rest lie-nine possible when negative surfaces 

 reached a stage of sensitiveness permitting an 

 adequate exposure in a fraction of a second. 

 With the improvements in the dry plate have 

 come a multitude of portable cameras, many of 

 them of great ingenuity. The earliest examples 

 were provided with an automatic exposer or 

 shutter, capable of speed adjustment to meet the 

 requirements of tho light and the amount of 

 motion to be overcome. A device, aided by an 

 exterior indicator, adjusted the focus by an eMi- 

 mate of feet, and provided for tho xise of the 

 universal focal point in the lens. A small cam- 

 era-obscura attachment enabled the operator to 

 locate the image. Recent modifications have 

 aimed at a reduction of weight, and at conven- 

 ient methods of storing plates or films within 

 the bn\. The panoramic idea has been worked 

 out with films and with paper rolls, and many 

 magazine forms have been adopted, though few 

 have been entirely satisfactory. Roll surfaces 

 are arranged to receive 100 or more impressions. 

 Magazines- for glass or cut films usually provide 

 for one or two dozen negatives. 



Among the cameras devised with a view to 

 unobserved operation there are many curious 

 forms. One German camera takes the shai>e of 

 VOL. xxxi. 40 A 



n l>ook. Another in operated in the Ut. Avert 

 camera has Id-en used in thin country, and 

 of the more conventional forma are placed in 

 caws resembling mitche!-., lunch ba-.. 



The development of the hand eamern ha* had 

 an important influence.' on the nrrnngi -merit of 

 cameras in general. Many of the later tl 

 cameras are now provided with a vat. 

 venicnt dc\icc. facilitating the use of i he cam- 

 era under conditions demanding readiness and 

 portability. Among the fanciful results of re- 

 cent Improvement! in rapid photography has 

 been the automatic arrangement that takes its 

 jilaee beside the weighing machine and the pub- 

 lic phonograph. The ' nickel-in-the-slot " | ho- 

 lographing machine resembles a round stove. 

 < >n opening the iron door a clockwork is seen be- 

 low, putting the whole mechanism in motion by 

 a spring. The principal featur ; is a vertical 

 axis acting as rotating power fora plate-catcher. 

 At the moment the piece of money is dropped, 

 shut ting off the electric current, a ferrotype plate 

 drops from a carrier and is caught by the catcher 

 and moved horizontally around a ring in a ver- 

 tical position. This ring contains several circu- 

 lar dipping baths of gutta-percha, into which 

 the plate, held by the catcher, is immersed and 

 then raised at certain intervals. The plate 

 passes first the collodion bath, after that the sil- 

 ver bath, and t'hen the bell sounds, warning 

 the sitter to be quiet, and the exposure takes 

 place. The plate now plunges into the developer, 

 washing bath, fixing bath, and again into water: 

 then it is moved outside of the circle and dried 

 over a flame. The entire process occupies about 

 two minui 



Sensitive Surfaces. Dry plates continue to 

 increase in sensitiveness, though makers are now 

 content to promise even an infinitesimal ad- 

 vance. The complaint that more attention is 

 paid to the attainment of rapidity than to abet- 

 tor image-bearing quality is often" justified. 



Gaedicke, of Berlin, has announced the inven- 

 tion of a collodion emulsion which is claimed to 

 be equal in sensitiveness to the most sensitive 

 gelatin emulsion. The new emulsion is said to 

 be easy to manipulate, and to be capable of pro- 

 ducing results rivaling those of any other meth- 

 od. The announcement is of particular interest 

 to those who have been loyal to collodion pro- 

 throughout all the advances of the pela- 

 tino-bromido emulsion. For certain 

 work, particularly for lantern positives, the col- 

 lodion processes have never been equaled by the 

 later prore- 



The practice of "backing" plates has come 

 into favor, especially among out-of-door work- 

 ers. Talbwt Archer mentions two backii :. 

 finding special favor in Kngland. The first is 

 bitumen dissolved in benzine and poured on the 

 back of the plate. It hardens in a few minutes 

 and is removed with the help of a broad chisel 

 before development. The other is a cream v mixt- 

 ure of burnt umber or burnt sienna with gum 

 and methylated spirit, applied with a piece of 

 wash leather and removed with a damp sponge. 

 K. .1. Wall recommends smearing black enamel 

 paper with glycerin and squeegeeing tho^ paper 

 upon the back of the negative. The object of 

 the backing is, of course, the prevention of 

 halation, and the precaution is valued, in all cases. 



