On Irrigation in Tasmania. 
87 
1st. The moistening of the soil when the rains fail. 
2nd. The effect of water as a substitute for other 
manure. 
3rd. The counteracting the summer frosts. 
4th. The destruction of the grub and caterpillar. 
As respects the first, viz. the supplying the want of 
rain, it should be observed, that, in the distribution of 
the rain throughout the year, Tasmania is circumstanced 
exactly like the tropical countries. Not only does 
almost the whole of the rain fall in about four months 
of the year, but in those months it all falls in a 
comparatively small number of days ; so that, omitting 
individual light showers, which have scarcely any effect 
upon the soil, there seem to be only about 30 or 40 
rainy days in the year over a great part of the Island, 
especially in the centre part of the low country. In 
Hobart Town there are more showers, perhaps, during the 
summer, owing to the vicinity of Mount Wellington. 
Indeed, in respect of the distribution of the rains, there 
is very little difference between Madras and Tasmania : 
in quantity, there is perhaps half as much again in the 
former as in the low country of the latter. In this very 
unequal distribution of the rains, the absolute necessity 
of artificial means of counteracting its ill effects is clearly 
shown ; and it is further established by the comparatively 
small quantity that falls altogether. In England, w r here 
the sun is much less powerful, the average fall of rain is, 
I believe, about 34 inches. I could not get complete rain 
tables for the occupied districts of this Island, but from 
what I w'as informed, and what I observed, it seems that 
the fall in the northern and southern parts of the low 
country cannot much exceed 20 inches—perhaps it does 
not equal it; and in the centre part it is still less. In a 
country so circumstanced the w ater that falls in the winter 
must be reserved in lakes and tanks till it is required in 
