TRANSACTIONS OF THE SECTIONS. 25 



The author then notices the performance of Mr. Whewell's and Mr. 

 Osier's anemometers, and observes, " It is very desirable that these 

 beautiful instruments should be placed beyond the limits of our own 

 island, particularly in the West Indies and at the Cape of Good Hope, 

 where they may measure the force of such a gale as no canvass can 

 withstand ; tliat which forces a ship to bare poles. 



" It is not only to measure the wind's greatest force that it is desi- 

 rable these anemometers should be multiplied and placed in different 

 localities, but that we may try, through their means, to learn something 

 more of the gusts and squalls which always occur during storms." 



Note on the Effect of Deflected Currents of Air on the Quantity of 

 Rain collected by a Rain-gauge. By Professor A. D. Bache, of 

 Philadelphia. 



The experiments referred to grew out of a report made at the request 

 of the British Association, on the quantity of rain collected at different 

 heights, whicli was presented at the Cambridge meeting of the Associa- 

 tion by Professor Phillips and Mr. William Gray, jun. Professor Rogers 

 was then present, and at his instance the author commenced a series of 

 observations about the close of the year 1833. Philadelphia, from the 

 extent of the plain on which it stands, is a good locality for such a pur- 

 pose. The observations were at first made by gauges placed at three 

 different heights. One of these stations was the top of a tower for- 

 merly used for making shot. The height of the tower is 162 feet. A 

 second was near the ground within the inclosure about the tower, and 

 the intermediate one was the roof of the university. The author's at- 

 tention was ultimately fixed upon the fact that the effect of eddy winds 

 upon the phenomena observed, Avas by no means a secondary one in 

 amount, and that he could not hope to deduce a law, nor to throw any 

 light on the nature of the phenomena, until this disturbing action was 

 got rid of. He has therefore thought that it might be useful to those 

 who may undertake similar experiments, to submit some of the evi- 

 dence of the effects which he attributes to deflected currents of air. 

 The observations on this point were chiefly made at the upper station, 

 on the top of the tower. The tower is square in its section, and the 

 alternate sides are nearly parallel and perpendicular to the meridian. 

 At the roof the horizontal section is about twelve feet on a side, and a 

 parapet wall, cut like a battlement, surroimds it. At first, one gauge 

 was placed at the N.W. angle of the tower, rising about six inches 

 above the parapet wall ; subsequently, a gauge for collecting snow was 

 placed at the S.W. angle ; and ultimately, four gauges, besides the ori- 

 ginal one, were placed at the four corners of the toMer, upon the para- 

 pet wall, above which they rose about ten inches. The rain gauges 

 consisted of an inverted cone, with a cylindrical rim, about five inches 

 in diameter, attached to the base, and a small aperture near the vertex ; 

 this fastened tightly upon a vessel serving as a reservoir. The snow 

 gauges were frustums of upright cones, the upi^er section being nearly 



