12 



NOTES ON PHOTO-ENGRAVING. 



I often have slightly enlarged or much reduced half-tones made 

 from my photos by the engraver. I used to send the negatives to the 

 engraver, but some were lost or injured, and they now do satisfactory 

 work from the prints. With these one can make various arrange- 

 ments of several pictures in one half-tone. At one time I thought 

 the half-tones were better when the backgrounds were not removed or 

 cut away by the engraver, but now I have them cut out whenever 

 practicable, as the picture usually stands out better when printed. 



LANTERN SLIDES. 



Most economic entomologists now have more or less teaching or 

 lecturing to do, and illustrations are necessaiy, especially as it is often 

 impracticable in large classes or audiences to use specimens. Large 

 charts are very useful, but I find the lantern slides are a much more 

 satisfactory and cheaper method of illustrating lectures. I was forced 

 into the making Of lantern slides of insects b} T classes too large to 

 permit of using and breaking specimens, oftentimes a lack of speci- 

 mens to illustrate the work of injurious insects, enough charts were 

 too expensive, and there were practically no slides of insects on the 

 market. Lantern-slide making is not a very difficult process. It can 

 not all be absorbed from books, however, but must be learned in the 

 school of experience. 



Whenever it will serve the purpose I use a 3^ by 4£ plate in photo- 

 graphing, then a lantern slide can be easily made from it by simple 

 contact exposure, as in making a print. One feels freer to destroy 

 poor negatives and try again when these smaller and cheaper plates 

 are used. A lantern-slide size negative can be made from a large 

 print, but I prefer to make slides direct from the large negatives in 

 the copying camera with lantern-slide attachments. Many negatives 

 do not have density or blackness of background sufficient to prevent 

 light getting through and making a darkish or muddy background on 

 the lantern slide. I constantly use a reducing solution with a brush 

 locally, as directed above, to clear up such backgrounds; it brightens 

 up wonderfully an otherwise dingy slide. This local reduction is one 

 of the most useful tricks I have learned about slide making. I save 

 all discarded negatives that are thin enough and cut them into cover 

 glasses for lantern slides. 



Coloring, well executed, adds much to the beauty and value of 

 insect lantern slides. To do this work properly requires high artistic 

 ability in the management of colors, deftness in applying them on so 

 small a scale, and an appreciation and intimate knowledge of the 

 insect being colored. I believe the day is not far distant when we can 

 photograph in colors by a much simpler process than that by which 

 the admirable three-color work used in the Butterfly and Moth Books 

 is accomplished. 



