793 
of Edinburgh, Session 1871 - 72 . 
Cold Periods. 
November 18 to December 10, or 23 days, 4°'6 under average, 
December 20 „ ,, 23, ,, 4 „ 3 0, 9 „ 
January 5 „ January 10, ,, 6 ,, 1°*0 ,, 
March 20 „ April 6, ,, 18 „ 3 o, 0 ,, 
Average, 51 days, 3 0, 4 „ 
Mild Periods. 
December 11 to December 19, or 9 days, 4°T above average, 
,, 24 ,, January 4, „ 12 ,, 3°*5 „ 
January 11 „ March 19, ,, 69 „ 3°’9 „ 
April 7 „ April 10, ,, 4 „ 6°-0 „ 
Average, 94 days, 4°*0 „ 
Hence during this period the temperature was under the average 
of the season on 51 days, the deficiency amounting to a mean of 
3 0- 4; and above the average on 94 days, the excess amounting to 
a mean of 4 o, 0. The most markedly mild period extended over 69 
days, viz., from 11th January to 19th March, during which the 
temperature was on an average of 3 0, 9 above that of the season; 
and as already stated, the temperature was, for the whole period of 
145 days, 1 0, 4 above the average. 
It may be concluded that in ordinary winters the stratum of 
water of uniform temperature will be thicker than Sir Eobert 
Christison found it to be this year in the beginning of spring; in 
other words, that it will be nearer the surface than 170 feet. 
In the end of last week, Mr James Leslie, C.E., kindly sent me 
some highly interesting and valuable observations on the deep- 
water temperature of Lochs Tay, Katrine, and Lomond, made by 
the late Mr James Jardine, C.E., in 1812 and 1814. These I 
have now very great pleasure in laying before the Society. They 
were taken in fathoms, and the temperature in degrees centigrade 
which are here reduced to Eng. feet, and degrees Fah. 
* The general results of these observations were given by Sir John Leslie 
in his “ Treatises on Various Subjects of Natural and Chemical Philosophy,” 
Edinburgh 1838, p. 281. 
