108 BULLETIN OF THE 



Every distinct group of three of the five given points in like 

 manner gives two solutions; hence of this kind there are in all 

 twenty solutions. 



Therefore, in general there are thirty spheres equally distant from, 

 five given points. 



The next communication was by Mr. H. A. Hazen 



ON THE RETARDATION OF STORM CENTRES AT ELEVATED STA- 

 TIONS, AND HIGH WIND AS A PROBABLE CAUSE. 



In the absence of Mr. Hazen the following abstract was read by 

 the Secretary, Mr. Baker : 



In his tenth paper, published in the January, 1879, number of 

 the American Journal of Science, Prof. Elias Loomis advanced 

 certain evidence, based on barometric observations, to show that 

 apparently the progress of a storm centre was much more rapid at 

 the surface of the earth than at elevations above it. It is the pur- 

 pose of this article to put forth certain facts which, it is hoped, will 

 tend to elucidate the subject. 



Not long since, before this Society, Prof. G. K. Gilbert showed 

 that a high wind had a tendency to depress the barometer column, 

 as determined from his discussion of certain observations made by 

 the Signal Service at the summit and along the side of Mount 

 Washington, New Hampshire. If now a wind can produce such 

 a depression, it would seem as if the wind accompanying a storm 

 and continuing its force at a high station some time after the pas- 

 sage of the storm centre at the base, might cause the apparent re- 

 tardation. 



It is very desirable that special experiments be made, under 

 natural conditions, directly testing the influence of high winds on 

 the barometer column.* 



It seems possible to indirectly ascertain such influence from a 

 barometric computation of the height of a mountain by means of 

 observations taken during different wind velocities. Table I gives 

 such a computation of the height of Mount Washington from ob- 

 servations at the base and summit in May, 1872 and 1873. 



* Direct experiments have been made, using a blower for the air current, and 

 an air-tight receiver for the barometer, at short distances, a condition of things, 

 however, which can never occur in nature. 



