176 OBSERVATIONS ON THE FALL OF RAIN. 
Considering it, however, as a wet year, Mr. 
Thom’s return would show, that for such a season, 
the water flowing from the district above the 
Greenock reservoirs, would be about two-thirds 
of the rain which fell. The proportion is as 
744 to 1088. 
The land draining into the Greenock reservoirs 
is high and mountainous, principally moorland, 
having a good deal of similarity to the moorland 
districts of Lancashire and Yorkshire, but of 
different geological character. Its formation is 
principally basaltic. It lies near the sea, on the 
east of the Firth of Clyde. 
Bute is an island, on the west of the Firth of 
Clyde, about sixteen miles in length, by four 
and a half in breadth. Where Mr. Thom’s ex- 
periments were made, it is comparatively a low 
country. It is, I believe, an undulating pastoral 
district, having no great elevations. The average 
rain for forty years, Mr. Thom states to be forty- 
eight inches. From its proximity to the sea and 
high land, it may be a favourable situation for a 
great fall of rain. 
