118 ASSOCIATION OF ECONOMIC ENTOMOLOGISTS. 



of the vertical front board and secured by the usual tripod screw. 

 The height of the entire apparatus from the floor may be easily 

 regulated to suit the convenience of the operator. The vertical posi- 

 tion of the camera allows convenient focusing, while the horizontal 

 position of the ol)ject table makes it easy to place the object upon 

 glass, as may be done over a white background to o))viate shadows, 

 or to so arrange the background as to make it absolutely black. I 

 have found greater difficulty in securing the black background with a 

 properly lighted subject than in getting a shadowless background. 

 The following method has been gradually developed : Upon the board 

 resting on the side arms I first place a sheet of thick cork. Over 

 this I spread a piece of heavy black velvet. The object is elevated 

 a few inches above the velvet ground upon a dissection needle held 

 in the cork, and the background below the object may then be shaded 

 from the light in such a way as to render it absolutely black. (See 

 PI. Ill, fig. 6.) I have found that mirrors may be used in illuminat- 

 ing an object with this arrangement without having difficulty with 

 the background. Medium isochromatic plates have proved to be 

 the best for general use, and the double-coated plates of this brand 

 are also an improvement upon the single coated. For label wor.k or 

 any subject consisting of black and white the contrast plates have 

 given best results. 



AA^iile I have found little use for photomicrography, the stand 

 described serves very well for the combination of the camera with the 

 microscope. 



Frequently in the experience of the economic entomologist there 

 arises the necessity for making enlarged views or charts for illus- 

 trative work under conditions Avhen lantern slides can not be used. 

 As I do not know that the process which we have used in making- 

 such charts has ever been used elsewhere, I will give an outline of our 

 method. 



The essential idea is to transmit a strong light through a negative 

 of which an enlargement is desired, projecting the image directly 

 upon the chart surface in a darkened room. The arrangement for 

 securing the projection (see PL III, fig. 7) may consist of a stere- 

 opticon lantern, or if only a cheap stereopticon is available, it will 

 do better to use only the portion of the stereopticon necessary for 

 lighting the negative and then use the camera lens in front of the 

 negative for the projection of the image. An arrangement such as 

 is often used in making lantern slides may be adapted to this work, 

 the negative-holding end of the camera being exposed to daylight 

 at a window which is entirely darkened around the camera box, and 

 the image projected upon the chart surface instead of upon the lan- 

 tern slide. The great advantage lies in the fact that all outlines and 



