1907-8.] On the Theory of the Leaking Microbarograph. 459 
anemogram, and the limnogram showing the alteration of seiche in the 
lake caused by the microbaric disturbance. 
If we can rely on the value of the velocity of propagation given in the 
table, it is easy to calculate from the breadth of the zigzag on the 
microbarogram that the breadth of this atmospheric disturbance must 
have been about 10 miles at Ardtrostan, and 13 at Killin. 
The following notes on the weather during the day may be of interest. 
The variation of the w T ind velocity may be seen at a glance from the 
anemogram reproduced in fig. 10. 
8 h 55 m Wind E. 2 (mile/hour). Cloud 1, cumulus towards S. Lake oily 
calm to S., slight ruffle from S.E. to N. The rain, which had begun about 
5 h , now came down in torrents. 
9 h 22 m Wind E. to S.E. 1 (mile/hour). Clouds 1, cumulus, drifting from 
W. 80° S., velocity 22. Rain stopped. Waves on lake slight from E. 
Wind rose about 9 11 35 m to 13 (mile/hour). 
9 h 45 m Wind S.W. Clouds 9, cumulus upper and lower. Drift of lower 
W. 75° S., velocity 45; drift of upper different, velocity say 22, direction 
also different. 
10 h 0 m Sun came out. 
10 h 25 m Wind E. Clouds 5, cumulus, drift from S.W. Waves cross 
ripples with oily patches. 
ll h 20 m Wind E. Clouds 9, cumulus. Waves from E. Shower at 
St Fillans, passing up the lake towards N.W. 
14 h 49 m Wind W. Clouds 9, cumulus, drift from S.S.W. Waves, a 
moderate swell with small black squalls at times. Shower at Lochearn- 
head, one of many there during the day. 
15 h 27 m Small cloudburst, which lasted two to three minutes. The 
drops whitened the surface like a shower of hail. 
18 h 27 m Wind W.S.W. Clouds 1, cumulus, drift from W. Waves from 
N.W., a few foam-crested. 
At Balimeanach the standard barometer fell from 28'736 in. at 9 h to 
28 , 608 in. at 22 h . The open-air temperatures at the same hours were 56*0° 
and 54*0°. The total rainfall during the 24 hours w r as 0’75 in. 
During the day the microbarogram was blurred by the characteristic 
wind vibrations, of which at times over 150 could be counted in an hour. 
Besides these, there occur irregular undulations on the traces, most marked 
at Killin, the times between the turning-points of which vary from 4 m to 
60 m or more. The traces at the three stations are by no means always 
similar. Thus, for example, there are two well-marked minima at Killin 
between 19 h and 20 h , with a maximum between them, the whole range 
