Geography of the Avr. 61 
which it is believed will prove important contributions to this 
question, but the results have not yet been published. It is im- 
portant in this connection to note experiments made by Cooper 
on the Frith of Forth Bridge, where a surface of 24 square 
metres, during a high wind, experienced a maximum pressure of 
132 kilogrammes per square metre, while a surface of 14 square 
decimeters showed, under similar conditions, 200 kilogrammes per 
square metre, by one instrument, and 170 by another. The opin- 
ion expressed by Cooper that in general the more surface ex- 
posed to the wind, the less the pressure per unit of surface, seems 
reasonable, and if verified by more elaborate experiments must 
have an important bearing. 
There are questions in connection with which even negative 
results are of an important character, particularly when such re- 
sults are quite definite, and tend to remove one of many unknown 
elements from physical problems of an intricate character. In 
this class may be placed atmospheric electricity, with particular 
reference to its value in connection with the forecast of coming 
weather. The Signal Office, through Professor T. C. Menden- 
hall, a distinguished scientist peculiarly fitted for work of this 
character, has been able to carry out a series of observations, 
which have received from him careful attention, both as to the 
conditions under which the observations were made and in the 
elaboration of methods to be followed. 
Professor Mendenhall also supervised the reduction of these ob- 
servations, and after careful study presented a full report of the 
work to the National Academy of Sciences, in whose proceedings 
this detailed report will appear. Professor Mendenhall says, 
“Taking all the facts into consideration, it seems to be proved 
that the electrical phenomena of the atmosphere are generally 
local in their character. They do not promise, therefore, to be 
useful in weather forecasts, although a close distribution of a 
large number of observers over a comparatively small area would 
be useful in removing any doubt which may still exist as to this 
question.” It may be added that Professor Mendenhall’s conclu- 
sions bear out the opinions expressed to the speaker, in a discus- 
sion of this question, by Professor Mascart, the distinguished 
physicist. 
It has been generally admitted that the aqueous vapor in the 
atmosphere plays a most important part in bringing about the 
formation of storms and maintaining their energy. It has been 
