8 THE MICROSCOPE Jan. 



ores of the Comstock lode at a depth of over 3,000 feet, 

 when they met with hot water. 



Should the minerals forming* the rock he too small to be 

 seen with the common lens, a microscopic section will 

 have to he cut. The process is a simple one, but requires 

 patient and skillful treatment to produce a section thin 

 enough for a full view of its structure. Mr. At wood had 

 two sections thus prepared from the hanging wall of the 

 Keyston mine, Amador county, at the thousand-foot level, 

 one to show color and texture, the other to be examined 

 by polarized light. 



The Microscope as a Detective. — The other day there 

 was a great robbery in South Africa of gold coins from a mail- 

 cart. They had been consigned in wooden cases. The thieves 

 took tlie gold out and filled the cases with sand. The police 

 have been uilable to discover where this exchange was made. 

 Why not employ the microscope ? Some years ago Ehrenberg, 

 that old prince of microscopists, was employed by the Prussian 

 Government to investigate a case of smuggling. A cask had 

 been opened, valuables extracted, and the case repacked and 

 shipped onward to its destination. The only clue to the crim- 

 inals was that the unpacking must have been done at some of 

 the custom houses through which the goods passed. 



To all appearance the microscope had a hopeless task. But 

 not so. Ehrenberg took some of the sand that had been used 

 [n the repacking, placed it under his microscope, looked through 

 his magic tube, and behold ! there on the stand lay a peculiar 

 specimen of foraminifera. That animal was found at only one 

 place in the world, and told just where the crime had been 

 committed. Possibly an examination of the sand found in the 

 South African cases, seeing they had travelled a great distance, 

 might l)y chance reveal the particul ir point in the route where 

 tlie theft took place, and thus lead the police to the trail of the 

 robbers. — Science Sif tings. 



