x 882.] 
Analyses of Books. 
297 
range of temperature from the coldest to the hottest month does 
not exceed 3 0 F. The average atmospheric pressure for the 
same years is 29*878 inches in the morning and 29*791 in the 
afternoon. 
The cloudiness is given on a scale where o denotes a perfectly 
clear sky and 10 total cloudiness. In this department we beg to 
suggest that more satisfactory results would be obtained with 
less trouble by means of Mr. Winstanley’s radiograph (see 
Journal of Science, 1881, p. 218), which records automatically 
both the duration of actual sunshine and its intensity. It will, 
perhaps, surprise some readers to learn that the skies of Trinidad 
are very far from cloudless. During the above-mentioned nine- 
teen years the lowest monthly cloudiness, for the months of 
February and November respectively, is 4*9 and 4*7, whilst in 
July and August it reaches 7*1. The atmospheric humidity is 
considerable, if i*ooo stands for perfect saturation of the air with 
aqueous vapour, the lowest degree of humidity, 0*674, is given as 
occurring in April and tfle highest, 0*841, in August. The 
average yearly rainfall for nineteen years, 66*39 inches, though 
about on a level with that of the rainiest parts of Britain, is not 
large for a region exposed to a tropical sun. The monthly rain- 
fall has its maximum, 11*28 inches in August, and its minimum, 
1*85 inches in April. The author remarks that one year, with the 
exceptional rainfall of 84 inches, he found in one part of the 
gardens the subsoil at the depth of 20 inches quite dust dry. 
The substratum in the Botanical Gardens is, probably, not 
direCtly moistened by the rain oftener than once in five or six 
years. 
InseCt pests are not wanting either in the gardens or in the 
island generally. The parasol-ants — probably the leaf-cutters — 
are said to have been unusually troublesome. We feel curious 
to know whether the nests have been attacked with the agencies 
proposed by our late friend, Thomas Belt — viz., carbolic acid and 
corrosive sublimate. Wasps and blight — probably aphides or 
scale inseCts — have also given annoyance. 
We find here a remark on the conditions of tree-life, which is 
worthy of careful consideration. Says the author: — “It is a 
regrettable faCt that the conditions of well-kept grounds are as a 
rule inimical to long-lived trees of majestic size and form. This is 
the case in temperate regions, but far more so here. The mis- 
chief arises from the removal of all fallen leaves and branches 
under the trees, which in a state of nature protect the roots from 
the sun and nourish the tree through them. It is well known 
that the majority of our forest trees, when their stems and base 
and surface roots are suddenly exposed to the sun, cease at once 
to thrive, and soon die outright. By the free admission of sun 
and air to the roots near the surface, the most harmful part of 
the dry season is intensified, and the beneficial influence of the 
wet season is greatly diminished.” It is to be noted that the 
VOL. IV. (third series.) X 
