SCIENCE- GOSSIP. 



ment can be used for testing and adjusting- 

 developers, testing media for dark room illumina- 

 tion, examination of light niters, testing plate 

 backings, etc. Although nearly all makers give 

 some indication on their packages with regard to 

 speed and other characteristics of their plates, the 

 conditions under which they make their tests are 

 not uniform. One very great advantage of the 

 little instrument is that it enables the actual user 

 of plates to ascertain quickly, and with a minimum 

 of trouble, the comparative usefulness of the 

 various brands on the market for his own special 

 purpose. The record obtained is a permanent one, 

 always ready for reference. The essential part of 

 the apparatus is a screen plate consisting of 

 a series of 25 tints of graduated densities, 

 each numbered for identification and comparison 

 with each other ; also a series of four small 

 coloured squares and a strip of grey numbered 1 

 to 5, all being approximately the same luminosity 

 and constituting what is known as the " Abney 

 Colour Sensitometer." Then there is a set of four 

 squares of special pure colour, each of which 

 represents a definite portion of the spectrum. 

 These colour squares are for testing the colour 

 sensitiveness of the plate ; also to ascertain the 

 most suitable colour for the source of light used 

 for developing. The light adopted for making the 

 test is by standard candle. Full working instruc- 

 tions are sent out with each plate-tester, by the 

 aid of which the youngest amateur should be able 

 to test each batch of plates, and thus to form a far 

 better judgment of required exposure and other 

 points about the plates. 



PHOTOGRAPHY FOR BEGINNERS. 

 By B. Foulkes-Winks, M.R.P.S. 



(Continued from Vol. VII., page 379.) 



Section I. Cameras {continued). 



In the "Adams" type of camera the bag system 

 employed is that known as the " Yale." By 

 this method the lifter, for lifting the plates, is 

 dispensed with entirely. This is accomplished by 

 a simple device, which raises the front plate 

 automatically, slightly above the rest, thus enabling 

 the operator to take hold of the sheath carrying the 

 plate and lift it into the bag, pressing it clown at 

 the back of the box. The simplicity of this chang- 

 ing will be appreciated by referring to fig. 2. This 

 shows a plate in the act of being pressed clown 

 into position after having been exposed. A minor 

 point of value in this system is, that the exposed 

 plates are always those which are first taken out 

 of the camera. Thus if only two or three are 

 exposed, the first plates taken out of the camera 

 are the ones exposed'. There is in this " Yale " 

 system of changing what is called a dividing sheath. 

 This is made thicker and more narrow than a plate 

 sheath, and is always inserted last. It is used 

 as a guide, as all the exposed plates are those 

 behind this dividing sheath. By feeling through 

 the bag, and counting the number of sheets 

 in the rear, it is always possible to ascer- 

 tain how many unexposed plates there are in the 

 camera. This sheath is made thick so that 

 it cannot pass the opening through which the 

 plates are lifted into the bag, thus rendering it im- 

 possible to twice expose the first plate. It is also 

 very useful when the plates are being developed, 

 as the operator will know that all plates behind 



this dividing sheath are those that have been ex- 

 posed. Of the cameras made by this firm the 

 li Yale " is unquestionably the most popular. It is 

 very small and neat in appearance, is fitted with 

 the firm's patent pneumatic regulation shutter 

 working between the lenses, giving a range of 

 speeds varying from j^gth to •§ a second, and time. 

 It has two " Adams " Real Image Brilliant View 

 finders, one for each way of the plate. A rising 

 front for both horizontal and vertical pictures, and 

 rackwork focussing. All the lenses are now fitted 

 with Iris diaphragms that work from outside the 

 body of the camera. We show an illustration 

 (fig. 1) of the No. 1 pattern (£5 5s.) fitted with an 



Yale " Camera. 



ordinary good class Rapid Rectilinear lens and 

 made for quarter plates. The No. 2 is fitted 

 with '• Cooke " lens working at F. 6'3, and is of 

 the new Anastigmat type of lens. The price of 

 this pattern is £10 10s. Od. No. 3 type costs 



Pig. 2. The " Yale " Changing System. 



£15 15s. Od., made for 5x4 plates, and is fitted 

 with a 6-inch Cooke lens F. 63. The No. 4 is fitted 

 with a 6-inch rapid rectilinear lens and made to 

 carry 5x4 plates, price £7 17s. 6d. In addition to 

 these four patterns the firm also make a stereoscopic 

 Yale camera. This is for plates 6f x 3J, giving 

 two pictures on one plate, each measuring 3 inches 

 square with a quarter of an inch space between. 

 The shutter works on the Adams pneumatic sys- 

 tem and. exposes both pictures simultaneously: it 

 is fitted with a pair of " Ross " 5-inch Aplanat 

 lenses, working at F. 7-5 ; price £12 12s. Od. The 

 same camera may be obtained fitted with a pair of 

 " Ross-Zeiss " 4^-inch convertible Anastigmat 

 lenses at F. 6'3. With these lenses the cost is 

 £22 10s. Od. All these cameras are constructed to 

 hold twelve plates, but they will carry twenty-four 

 cut films instead if it is desired to work with films. 

 (To be continued.) 



