250 Fortieth Annual Meeting 



objects as shown (in lantern slide) Avas found to be satis- 

 factory for such specimens as could be photographed 

 readily in the air by ordinary methods. I first secured a 

 large sheet of the best quality double strength window glass. 

 By breaking the large end of a small three-cornered file in 

 such a way as to form a sharp cutting corner, a tool can 

 be made which when fastened into a small hand drill makes 

 it possible to bore any number of holes into the glass that 

 may be required. To drill a hole, scratch the surface of the 

 glass slightly at the desired place with the file point, then 

 lay a small round lump of putty or soap as large as a thimble 

 on the table beneath the scratch on the sheet of glass and 

 with the file-drill proceed carefully to burr out a hole on the 

 upper surface of the glass. When half way through turn 

 the glass over and drill from the opposite side until the holes 

 meet. The opening thus formed is then easily enlarged by 

 carefully rasping it out with the spike on the small end of 

 the file. With two or three holes close together, it is 

 obviously easy to firmly fasten with a cord or by other 

 means a variety of large objects to the glass. 



The glass when stood upright in a grooved pedestal forms 

 a transparent supporting screen through which the light as 

 well as the shadow of the object to be photographed will 

 readily pass. By locating the camera, the object to be 

 photographed, and the background between two windows 

 as shown (slide), it is possible to secure a photograph of 

 any object held on the glass screen in the way just shown 

 that will be entirely free from the undesirable and confusing 

 shadows that the object would cast if placed directly in front 

 of an opaque background. 



The next improvement in the use of the screen was the 

 discovery that a number of objects could be attached to the 

 glass screen in any desired arrangement without injuring 

 the specimen by simply sticking them in place with a few 

 drops of hot paraffine. In this way, for example, plates 

 with a number of heavy lava specimens were prepared, the 

 single specimen sometimes weighing a pound or more. By 



