yt 
The Method of Concussions. 55 
ties, among them that of exploding the gas in the balloon itself 
when high in the air. His conclusions, as stated by himself in 
his first report, were (page 59) : 
First. That when a moist cloud is present, which, if undisturbed, would 
pass away without precipitating its moisture, the jarring of the cloud by 
concussions will cause the particles of moisture in suspension to agelom- 
erate and fall in greater or less quantity, according to the degree of moist- 
ness of the air in and beneath the cloud. 
Second. That by taking advantage of those periods which frequently 
occur in droughts, and in most if not in all sections of the United States 
where precipitation is insufficient for vegetation, and during which at- 
mospheric conditions favor rainfall, without there being actual rain, pre- 
cipitation may be caused by concussion. 
Third. That under the most unfavorable conditions for precipitation, 
conditions which need never be taken in operations to produce rain, storm 
conditions may be generated and rain be induced, there being, however, 
a wasteful expenditure of both time and material in overcoming unfavor- 
able conditions. 
His second report has not been published, but I infer that his 
second series of observations were believed by him to confirm 
the results of the first. 
Mr Dyrenforth generally omitted one check which he might 
well have employed, and which I personally urged him to em- 
ploy. Experiments of this sort, made in the free air, with the 
accompanying conditions not under control, should be accom- 
panied with every possible check ; and one self-evident and very 
necessary one is the observation of a physicist familiar with the 
meteorologic side of physics. Such an expert (Mr G. E. Curtis) 
accompanied the party in its first experiments. His report (ex- 
cept the bare meteorologic record made during the experiments) 
does not accompany Dyrenforth’s document. It was presented, 
however, to the Philosophical Society of Washington, and was 
printed elsewhere. Mr Curtis says, substantially, that an explo- 
sion in a cloud brings down a few scattering drops of rain, and 
this may happen even with an explosion on the ground, if heavy. 
Otherwise he says there was no rain-making. It is but fair to 
say that with Mr Dyrenforth’s report are given the reports of his 
assistants, Mr John T. Ellis, Lieutenant 8. A. Dyer, and Mr Eu- 
gene Fairchild, and they were stronger in the expression of a 
belief that rain was successfully made than is Mr Dyrenforth ; 
and there are also many favorable quotations from spectators. 
