

PRESIDENTIAL ADDRESSES. 551 



and Miiller, 1 Spottiswoode, 2 Moulton, 3 Grove, 4 

 Crookes, 5 Schuster, 6 J. J. Thomson 7 , and 

 Fleming, 8 almost a complete history of the 

 new province of electrical science which has grown 

 up, largely in virtue of the great modern improve- 

 ments in practical methods for exhausting air from 

 glass vessels, culminating in Sprengel's mercury- 

 shower pump, by which we now have " vacuum 

 tubes " and bulbs containing less than i Q I OOQ of 

 the air which would be left in them by all that 



1 Roy. Sec. Proc. t vol. 23, 1875, p. 356; vol. 26, 1877, p. 519; 

 vol. 27, 1878, p. 374 ; vol. 29, 1879, p. 281 ; vol. 35, 1883, p. 

 292; vol. 36, 1884, pp. 151, 206; Phil. Trans., 1878, pp. 55, 

 155 ; 1880, p. 65 ; 1883, 477. 



2 Roy. Soc. Proc., vol. 23, 1875, pp. 356, 455 ; vol. 25, 1875, pp. 

 73, 547 5 vol. 26, 1877, pp. 90, 323 ; vol. 27, 1878, p. 60 ; vol. 29, 

 1879, p. 21 ; vol. 30, 1880, p. 302 ; vol. 32, 1881, pp. 385, 388; 

 vol. 33, 1882, p. 423; Phil. Trans., 1878, pp. 163, 210; 1879, 

 165 ; 1880, p. 561. 



3 Roy. Soc. Proc., vol. 29, 1879, p. 21 ; vol. 30, 1 880, p. 302 ; 

 vol. 32, 1881, pp. 385, 388; vol. 33, 1882, p. 453; Phil. Trans., 

 1879, p. 165 ; 1880, p. 561, 



4 Roy. Soc. Proc. vol. 28, 1878, p. 181. 



5 Ibid. 1879, pp. 347,477; Phil. Trans., 1879^.641; 1880, 

 p. i 5 ; 1881, 387. 



6 Roy. Soc. Proc., vol. 37, 1884, pp. 78, 317 ; vol. 42, 1887, p. 

 371 ; vol. 47, 1890 ; pp. 300, 506. 



7 Ibid. vol. 42, 1887, p. 343 ; vol. 49, 1891, p. 84. 

 * Ibid. vol. 47, 1890, p. 1 1 8. 



