TRANSACTIONS OF SECTION A 551 



6. S'ur les Series Hypergeometriq'ues. By Professor Halphen. 



([This paper was ordered by the General Committee to be printed in extenso, but 

 is omitted by desire of the Author.] 



TUESDAY, SEPTEMBER 6. 



The following Reports and Papers were read : — 

 1. Report of the Comtiiittee on Electrical Standards. — See Reports, p. 423, 



2. Report of the Committee for the measurement of the Lunar Disturbance 

 of Gravity. — See Reports, p. 93. 



3. On the Rainfall Observations made upon York Minster by Prof. 

 John Phillips, F.R.S. By G. J. Stmons, F.R.S. 



The author commenced by noticing the experiments on rainfall made by ]Mi'. 

 Townley and by Dr. Ileberden at Westminster in 1766, and elsewhere. Those by 

 Prof. Phillips and Mr. Gray were made during the years 1832-5, when gauges were 

 set up at York, with the following results : — 



MuseUm garden, 2 inches above ground. Total rain 21 'SI in. Patio 100. 



„ roof, 44 feet „ „ „ „ 17'39 „ „ ftO. 



Minster Tower, 213 feet „ „ „ „ 12-99 „ „ 60. 



Which totals agree very well with Dr. Heberden's observations. Prof. Phillips' ex- 

 planation of the above was that the drops of rain increased in volume on their 

 •descent through the moist lower strata of the atmosphere. The author remarked 

 upon certain considerations which liad been omitted by Prof. Phillips, such as the 

 velocity of tlie wind and the fact that seasons which are ^^'indy are also cold and 

 humid — and to Prof. Bache's report, presented to the British Association in 1838, 

 in which he called attention to the important effect of eddy winds on the phe- 

 nomena. He found that, of gauges mounted upon a lofty tower, those to leeward 

 of the wind received the most water. A great alteration was made by elevating 

 the gauge on a pole ; thus, when those at the N.E. and S. W. angles received water in 

 the proportion of 1 to 1'68, those elevated 6 feet above the parapet received it in 

 the proportion of 1 to 1-08, and with a more moderate wind the quantities were yet 

 nearer equality. Sir John Herschel also has shown that any sensible addition to 

 the volume of a drop of rain in the way supposed would very materially raise its 

 temperature. The author then adverted to Mr. W. S. Jevons' paper, published in 

 the 'Philosophical Magazine' for Dec. 1861, in which he shows that the phenomena 

 observed are all consistent ^\^th the theory that the fall of rain is practically identi- 

 cal at all elevations, while the observed differences are due to imperfect collection 

 by the gauges, owing to deflection of the rain-bearing current by such obstacles as 

 ■houses, towers, and even the gauges themselves. Mr. Dines (without knowledge 

 of the last paper) came to a similar conclusion, as stated to the British Association 

 in 1877, and this had subsequently been confirmed by observations on large surfaces, 

 such as the roof of Messrs. Marshall's factory at Leeds, and upon one 5,000 square 

 feet in area in survey. In the latter case (the height above the gi-ound being 29 

 feet) the difference between the rainfall on the two localities was only 2 per cent. ; 

 instead of 20 per cent., as woidd be the case on the roof of a small building or near 

 the edge of a large one. 



