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the day before, or (3) at 9.0 a.m. and entered for the day on 
which the readings are taken. I adopt (3), believing it to be not 
only the most rational, but also the most general plan ; but at 
the Greenwich Observatory, they follow (1), whilst the British 
Meteorological Society recommends (2). 
In reading the graduated measure, the level of the water is 
to be taken to the nearest graduation, whether above or below, 
giving the benefit of a doubt to the higher one. This will, 
from month to month, compensate fairly for loss due to evapo- 
ration and capillary adhesion to the sides of the receiver. Some 
observers read oftener than once in twenty-four hours in hot 
weather, the better to avoid the consequences of evaporation, but 
I doubt this being necessary, at any rate for general purposes. 
Snow is to be melted, and the product treated as rain ; but, 
except when the fall is slight, the rain-gauge must be super- 
seded, or snow may be lost, owing to wind having blown it out 
of the funnel ; and still more, owing to the funnel being inca- 
pable of containing any considerable depth of it. The thing to 
supersede the gauge is a cylindrical tube of the corresponding 
diameter. Let this be pressed down, in a vertical direction, 
through the snow, to the ground, and the snow which is forced 
into it will be the amount from which the measurement of the 
water should be sought. “ The proportion of snow to water is 
about 17 to 1 ; and of hai], to water, 8- to 1. These quantities, 
however, may vary, according to the circumstances under which 
the snow or hail may have fallen, and the time they may have 
been on the ground.” * 
In frosty weather, persons using Howard’s gauge will do well 
to replace the earthenware jar by a glass wine-bottle, inserted 
in some larger water-tight vessel. If the frost bursts the bottle, 
the damage done is trifling in pecuniary value, and the contents 
are saved by the external receptacle. 
Hygrometry. — Hygrometry is that department of Meteorology 
which deals with the moisture (scientifically called aqueous 
vapour) which is present in the atmosphere. Tomlinson’s re- 
marks cannot be improved upon: — “The condition of the air 
as to moisture and dryness is of the greatest importance, not only 
in the science of the weather but also in domestic economy, in 
regulating many processes of art, and in directing the purchase 
and selection of various articles of produce. A good hygrometer 
will detect the dampness of a room, and indicate the condition 
of a magazine, a hospital, or sick ward. Some operations in 
the useful arts require dry rooms, others an air inclining to 
dampness ; some warehouses also require to be dry, others 
moderately damp, while hot houses, green houses, &c., require 
* Tomlinson’s Rain-cloud, p. 118 (a very useful book). 
