6 DEPARTMENTAL REPORTS. 



bulletins give complete information as to the depth and character of 

 snowfall in the mountains — data that have such an important bearing 

 on summer water supply for irrigation purposes. 



ETHERIC SPACE TELEGRAPHY. 



Substantial improvements have been made during the past year in 

 the Weather Bureau system of wireless telegraphy. The line of 

 research has been divided into three classes: First, the perfection of 

 a more powerful transmitter, in which the energy of radiation shall 

 be greatly increased; second, the devising of a more delicate receiver, 

 one that would be positive instead of depending upon an imperfect 

 and variable contact, as do all systems now in use; and, third, the 

 perfection of a system of selective telegraphy whereby messages can 

 be differentiated and only the receiver that it is desired shall receive 

 the message become responsive to the waves of ether. 



The first of these problems may be said to have been successfully 

 solved, and a transmitter devised capable of radiating all the energy 

 generated; the second is believed to be nearing a successful solution; 

 the third is thought to be well demonstrated theoretically, but has 

 not been fully tested in practice. 



While there is much experimental work yet to be done before our 

 system, or any system of which I have knowledge, is reliable for inter- 

 ship communication, or before any two systems can work within the 

 same field without each rendering the other useless, such progress has 

 been made by the Government experimenters that, with no interfer- 

 ence by private systems, stations can be successfully operated over at 

 least 150 miles of coast line, and they are now in operation on the 

 North Carolina and Virginia coasts, and soon will be instituted 

 between the Farallone Islands and the mainland, and Tatoosh Island 

 and the mainland, on the Pacific coast. 



If a system of selective telegraphy can not be perfected so that one 

 system does not interfere with and render useless another, and thereby 

 prevent all use to commerce of recent discoveries in wireless teleg- 

 raphy, it may become necessary, on account of the value of these dis- 

 coveries to our marine interests, for the Government to take exclusive 

 control of all systems of etheric space telegraphy and to establish 

 stations along our extensive coast lines at such distances and in such 

 relation, the one to the other, that they shall not interfere. Even 

 then there will occasionally be difficulty in communicating with the 

 mainland whenever two ships in close proximity are attempting to 

 transmit or receive messages at the same time. 



DESTRUCTION OF HAILSTORMS WITH CANNON. 



Considerable interest has been aroused among agriculturists in 

 the United States relative to the prevention of hailstorms by the use 

 of explosives fired from specially designed cannon. The experiments 

 conducted along this line by grape growers of France and Italy have 

 aroused popular interest in this country. The theory is not a new 

 one, though perhaps not so ancient as the idea that precipitation 

 occurs soon after and as a result of the explosives used in battles. 

 As early as 1769 the Marquis de Cheviers, a retired naval officer of 

 France, thought that he could combat the scourge of hailstorms by the 

 firing of cannon, but his experiments, like those conducted by many 

 others at various times during the past century, were not productive 

 of definite results. 



