108 THE AMERICAN MONTHLY [June 



1,200 went out on the "Washing-ton." While letters 

 could be carried out they could not be brought in by 

 balloon. Carrier pig-eons were therefore sent out with the 

 balloons and permitted to bring back dispatches. These 

 had to be lig-ht enough in weight for the pigeons to carr}'. 

 Photo-micrography wavS therefore resorted to. Messages 

 were copied on a single sheet of paper and then reduced 

 to the most minute proportions. On their arrival in Paris 

 the characters were enlarged by the microscope. Each 

 message was then copied on a card and forwarded to the 

 person addressed. Each word cost ten cents and each 

 messag-e was limited to twenty words. Later the mes- 

 sages were printed from type and reduced still farther. 

 They were put on pieces of paper 1}{ by 1)4 inches. The 

 collodion films were rolled and enclosed in small quills 

 which were sewed to the tail feathers of the pigeons. 

 The collodion films were ten times thinner and lighter than 

 paper. On arrival, in l*aris, the quills were split open and 

 the films rapidly unrolled in water containing a few drops 

 of ammonia. The films were then dried and enclosed 

 within two plates of glass. They were then ready to be 

 deciphered by the microscope. This mode of reading 

 was later supplanted by a projecting lantern and' electric 

 light. When thrown upon a large screen four trans 

 scribers could work at once on each sheet contained 1,600 

 messages. At a later time, the films were photograghed 

 back to the scale of the original printed matter so that 

 each section was enlarged from the most minute dimen- 

 tions to a form that could be read with perfect ease. 

 Then the telegrams were separated by scissors and each 

 person received a dispatch in fac-simile to the original 

 printed matter. Many of these dispatches are today 

 exhibited as specimens of photomicrography. 



Milk. — In Dr. Julius Nelson's investigation it was found 

 that milk in a cow's udder may have as high as 10,000 

 bacteria per drop, that first drawn being most infected. 



Wanted: — Petrological microscope with accessories for 

 petrological work, instrument to be of superior grade and 

 in good condition. Send description and price. 



