90 
THE FRESH-WATER LOCHS OF SCOTLAND 
observation planned to test a totally different hypothesis. I had 
supposed that the vibrations might be due to some extent to simul- 
taneous abrupt or periodic disturbances of the atmospheric pressure. 
As explained above (p. 36), the statolimnograph can be used in 
rapid alternation as a limnograph and as a microbarograph. Fig. 34 
shows the result of an observation of this kind. The limnogram is 
deeply embroidered ; the microbarogram is all but straight. Since 
the sensitiveness of the Richard statoscope is fifteen to twenty times 
that of a mercury barometer, the ordinate of the microbarogram 
represents the air-pressure on a larger scale than a water barometer. 
If M^e allow for the damping effect of the well and access tube on the 
half-minute vibrations, we shall be under the mark if we admit that 
Fig. 34. 
the statolimnograph magnified the range of these vibrations three 
times. The obvious conclusion is that there was no disturbance of 
the atmospheric pressure of an order sufficient to cause directly the 
embroidery observed on the limnogram. It follows that it must 
have been due to some cumulative atmospheric cause whose action 
originated at a distance from the observers, and I am inclined to look 
for this cause in the surface waves, solitary or periodic or quasi- 
periodic, caused by the heaping action of the wind. It is, of course, 
obvious that such action as this would be screened off by a promontory 
or an island, and would be most marked at the windward end of a 
lake. This cause was suggested, under the name of Windstau^ by 
Endros in his classical memoir on the complicated seiches of the 
Chiemsee, which has done so much to enlarge our knowledge of lake 
oscillations. 
