and Laboratory Methods. 2-283 



special copying stand in which the book is pressed flat against a plate glass sur- 

 face by blocks and screws from behind ; have employed expensive lenses from 

 a sixteen-inch anastigmat downwards; have tried all kinds of plates (with a pref- 

 erence for a process plate or lantern slide); and yet with all these advantages I 

 have not succeeded in getting any better results than are obtainable by the 

 simple procedure I am about to describe. 



Most cuts in books are about the right size for making lantern slides, so that 

 in a general way they require to be copied at the same size, or on a slightly 

 reduced scale. Whilst reading a recent work on photographic optics I was 

 much impressed with the great depth of focus obtainable by stopping down a 

 short focus lens, and the idea flashed into my mind that it could be utilized in 

 using a small fixed focus hand camera for making my negatives from books ; 

 and I proceeded at once to test it. Amongst quite a collection of cameras I 

 possess an Eastman Bullseye kodak, a small affair carrying a 3^ x 3i film, and 

 armed with a five-inch fixed focus lens. I ascertained by means of a set of opti- 



Fu;. 1. — A carcinomatous stomach photographed direct from 

 specimen (under water) with kodak and supplemental -\- ?j 

 lens at 15 inches. 



clan's test glasses what strength of supplemental spectacle lens was required to 

 bring a cut in a book on to the ground glass full size, and found I could do it 

 with a 5^-inch (7 diopter) lens, and that I could obtain the image half the size 

 with a 13-inch (3) lens. The distance of object from lens was in the first case 

 7^ inches, in the second 12 inches. I could have worked this out by formula, 

 but it is easier for me to test than calculate. I now knew that I could photo- 

 graph an object half natural size at 12 inches distance therefrom if I put a 13- 

 inch or 3 diopter spectacle lens in front of my kodak lens. I had further learned 

 from the book I had read, that if the lens were stopped down to F-45 or F-60 I 

 should have a focal depth of about six inches ; in other words, I could put my 

 camera nine inches from the cut to be copied, or fifteen inches, and get a sharp 

 picture in either case. This I proceeded to test. I put a book open on the 

 table, and above it on the ring of a retort stand I placed my camera with its sup- 

 plemental lens and small stop, and I proceeded to make a series of copies at 



