In the frost, as in clear summer weather, it lies constantly at the bottom; and in snow, as in rainy weather, it pitches its dwelling upon the very mouth of the phial.
What reasons may be assigned for these circumstances I must leave philosophers to determine, though one thing is evident to every body, that it must be affected in the same way as that of the mercury and spirits in the weather-glass. It has, doubtless, a very surprising sensation; for the change of weather, even days before, makes a visible alteration upon its manner of living.
Perhaps it may not be amiss to note, that the leech was kept in a common eight-ounce phial glass, about three-quarters filled with water, and covered on the mouth with a piece of linen rag. In the summer the water is changed once a week, and in the winter once a fortnight. This is a weather-glass which may be purchased at a very trifling expense, and which will last I do not know how many years.
I am, &c.
J. F.
NATURALISTS’ CALENDAR.
Mean Temperature 44·82.