﻿226 Lord Kelvin and Mr. Magnus Maclean on 



and that the incessant variations of electrostatic force which 

 he had observed, minute after minute, during calms and light 

 winds, and often under a cloudless sky, were due to motions 

 of large quantities of positively or negatively electrified air in 

 the immediate neighbourhood of the place of observation. 



§ 2. It was proved* by observations in the Old College of 

 Glasgow University that the air was in general negatively 

 electrified, not only indoors, within the old lecture-room f of 

 Natural Philosophy, but also in the out-of-doors space of the 

 College Court, open to the sky though closed around with 

 high buildings, and between it and the top of the College 

 Tower. The Old College was in a somewhat low situation, 

 surrounded by a densely crowded part of a great city. In 

 the new University buildings, crowning a hill on the western 

 boundary of Glasgow, similar phenomena, though with less 

 general prevalence of negative electricity in the air, have been 

 observed, both indoors, in the large Bute Hall, and in many 

 other smaller rooms, and out-of-doors, in the court, which is 

 somewhat similar to the courts of the Old College, but much 

 larger. It is possible that the negative electricity found 

 thirty years ago in the air of the Old College may have been 

 due to its situation, surrounded by houses with their fires, and 

 smoking factory-chimneys. In the New College much of the 

 prevalence of negative electricity in air within doors has, how- 

 ever, been found to be due to electrification by the burning 

 lamp % used with the quadrant-electrometer ; and more 

 recent observations, with electrification by flame absolutely 

 excluded, throw doubt on the old conclusion, that both in 

 town and country negative electrification is the prevailing 

 condition of natural atmospheric air in the lower regions of 

 the atmosphere. 



§ 3. The electric ventilation found in the Old College, and 

 described in § 299 of ' Electrostatics and Magnetism,' accord- 

 ing to which air drawn through a chink, less than J-inch 

 wide, of a slightly open window or door, into a large room 



stratum near the earth's surface. On the two or three occasions when 

 the in-door atmospheric electricity was found positive, and therefore the 

 surface of the floor-walls and ceiling negative, the potential outside was 

 certainly positive, and the earth's surface out-of-doors negative, as usual 

 in fine weather." — Ibid. § 300. 



* Ibid. Q. 2, § 283. 



t Ibid. §§ 296-300. 



X "Electrification of Air by Combustion," Magnus Maclean, M.A., 

 F.E.S.E., and Makita Goto, Philosophical Society of Glasgow, ISov. 20, 

 1889; "Electrification of Air by Water-Jet," Magnus Maclean, M. A., 

 F.R AE., and Makita Goto, ' Philosophical Magazine,' August 1890. 



