374 
Scientific Intelligence. 
the thatch), nearly cut through. It has been observed, that 
mice are more numerous during wet than dry seasons ; and this 
season they are more numerous than usual. During the winter 
of the year in which they were numerous beyond all others, a 
long-continued and severe frost took place, and they then dis- 
appeared. It is supposed they perished from want of food or 
water. All opinions regarding the amount of damage done 
by these mice to the pastures, are mere conjectures, but it 
must have been very considerable. In one tenement in Moi- 
dart, having a stock of 2000 sheep, it was estimated as equal to 
tliat of 300 sheep of an over stock. In Ardgour, on the grounds 
around Colonel Maclean’s residence, the mice destroyed an im- 
mense number of fir plants, and other young trees, by eating 
away the bark a little above the root. So bent w^ere they here 
on mischief, that old women, with cats, were stationed at diffe- 
rent points, in huts, through the plantations ; at least it is gene- 
rally reported that such w’as the case. It is not likely that these 
establishments could give any effectual check to their depreda- 
tions. It is not probable that there was any thing like an hwa- 
slon of this country by the mice, at the time they were so un- 
commonly numerous. It is more probable, that there was some- 
thing in the season peculiarly favourable to their increase. There 
are always a considerable number of field-mice in the woods, 
where they live by hoarding up, under ground, great quantities 
of hazel-nuts ; and in soft, moist ground, where them is long 
rank grass, or where the ground is coated with moss or fog, 
many of their nests and roads may be found under cover of the 
moss or grass. No facts occurred that would lead one to sup- 
pose that they migrate from one district of country to another. 
28. Salmon Fisheries In the River Tay. ~ The salmon 
fisheries of the Tay may be divided into classes, the River 
Fisheries and the Frith or Sea Fisheries. The propriety of 
this distinction will readily appear by attending to the migrations 
of the salmon, and the most successful methods of capture, as 
these depend upon differences in the condition of the w^ater in 
the River and in the Frith. Salmon, though inhabitants of the 
sea, approach the shores, enter our large rivers, and mount to- 
wards their sources, for the purpose of depositing the spawn in 
their gravelly beds. As soon as this object is accomplished, 
