Mr Anderson’s New Jtmometer. 67 
The measure of evaporation thus found, is expressed in 
inches and decimals of an inch, by means of an attached scale 
GH, the divisions of which are determined by experiment. 
Suppose, for example, that the instrument is exposed to simile 
circumstances with an evaporating basin, and that the quantity 
evaporated from the latter in a given time, as determined either 
by weight or measurement, is found to be one-tenth of an inch, 
while the alcohol distilled by the former in the same time, fills 
the tube AB to the depth of one inch, then the scale being 
divided into inches and tenths, will indicate tenths and hund^- 
redths of an inch of evaporation. By increasing the proportion 
between the diameters of EF and AB, the quantity of evapora- 
tion may be measured to any degree of minuteness required. 
In using the instrument, the tube EF is to be sheltered from 
rain by inclosing it in a case or cover, to prevent its temperature 
being reduced below that of the atmosphere by subsequent eva^ 
poration ; and the bulb BC is to be kept constantly moist by 
means of a small cup containing water attached to the tube im- 
mediately below it, the silk or paper being in contact with the 
water, or from an adjoining vessel, as in the case of the hygro- 
meter. The instrument is placed in a vertical position, and is 
prepared for a new observation by inverting it, so that the dis- 
tilled alcohol may be conveyed back to the tube EF. It is to 
be hoped, that this beautiful and ingenious contrivance will soon 
meet with that reception among meteorologists, to which its 
merits so well entitle it. This atmometer has already been con- 
structed, and is found to possess the utmost delicacy. It is 
probable that it may in time supersede the use even of the hy- 
grometer. 
Art. Xl.^SJcetch of the Distribution of Rocks in Shetland. 
By Samuel Hibbert, M. D. M. W. S. &c. (Continued 
from Vol. I. p. 314.) 
In the former part of my paper, I commenced with describ- 
ing the more southerly strata of Shetland, situated at Fitful 
Head, which were found to consist principally of clay-slate, 
with the addition of gneiss and mica-slate. Tracing them from 
the south, the whole were observed to be intercepted in their 
E 2 
