TRANSACTIONS OF SECTION A. 



54a 



10. On the Arrestation of Infusorial Life by Solar Light. By Professor 

 John Ttndall, F.B.S. — See Reports, p. 450. 



Fig. 1. 



11. On a netv Integrating Anemometer, By the Rev. J. M. Wilson, M.A., 



and H. S. Hele Shaw. 



The primary object of this instrument is to obtain a record of the total trans- 

 ference of air over any given spot, in order to be able to arrive at a determination of 

 the circulation of air on the globe, in a similar way to that in which the circulation 

 of the water is known to take place. Few results would be so interesting as 

 a map of the world showing the simultaneously existing air-currents, so as to enable 

 the average circulation of the whole to be seen at a glance. The existing anemome- 

 ters only give the resultant after considerable labour in calculation, by takino' 

 the average direction and velocity for short 

 periods, first by resolving the various com- 

 ponents, then summing and recombining 

 them. The tedious and inacciu-ate nature 

 of this process is obvious. JNIr. Wilson, 

 therefore, conceived the idea of having a 

 pencil moved over a board in the direction 

 of, and with a velocity proportional to that 

 of, the wind, and submitted a sketch of a 

 plan based upon this idea to Mr. Shaw, 

 who has undertaken the complete design 

 and superintended the construction of the 

 first instrument, which, however, must be 

 considered rather in the light of an experi- 

 mental one. The ordinary cup-anemometer 

 of Robinson is xised to drive a train of wheels 

 by means of a central spindle on which is 

 a worm — and thus iiltimately to turn, at a 

 much reduced speed, a serrated roller, which 

 gives motion to a horizontal table, and on 

 this is laid the sheet of paper. The plane 

 of rotation of the roller is always kept co- 

 incident with the direction of the wind, by 

 having its bearings in a hollow rod which 

 contains the central one, and which only 

 turns as the wind changes its direction ; 

 thus the curve is identical in direction with 

 the wind. The board and paper are pro- 

 tected by a sloping wooden roof, which 

 supports a pillar five feet high, carrying 

 the cups and direction-vanes. The original 

 plaa was to have the board, which is two 

 feet square, moving on truly spherical steel 

 balls, upon a marble slab four feet square. 

 The much better arrangement is now used of 

 a pair of light wrought-iron frames, moving 

 by means of flanged rollers in directions at 

 right angles to each other, the upper on the 

 lower, and the lower on the marble, kept parallel by having rollers running in the 

 frame which supports the roof. By this means a movement can be obtained in any 

 direction whatever without anj' rotation being able to take place, and the results 

 obtained during the few days in \\hich the instrument in its completed form has 

 been at work are very satisfactory. Fig. 2 shows the curves obtained from August 

 •"lO to September -3, combined so as to give at a glance the direction and volume of 

 wind passing over University College, Bristol, during that time. The trace of the 



Integrating Anemometer. 

 (N.B. D is,fastened to and supported 

 by the frame, and not to the ver- 

 tical spindle.) 



