THE ESSEX FIELD CLUB.
91
from shrubs, trees, walls, and buildings—at the very least, as many feet from
their base lines as they are in height. Tall-growing flowers, vegetables, and
bushes must be kept away from the gauge If a thoroughly clear site cannot be
obtained, shelter is most endurable from N.W., N., and E., less so from S.,
S.E., and W., and not at all from S.W. or N.E. The funnel must be set
quite level, about I ft. above grass, and should be so firmly fixed that it will
remain so in spite of any gale of wind or ordinary accidents. Its correctness
in this respect should be tested from time to time, and if the funnel of a
japanned gauge becomes so oxidised as to retain the rain in its pores, or threatens
to become rusty, it should have a coat of gas tar, or japan black, or a fresh
funnel of zinc or copper should be provided.
Having got the rain into the bottle, the next thing to find out is its amount;
that you do quite as easily and much more pleasantly than when you have
to take a dose of medicine; for
measuring a dose of medicine you have
a glass marked with certain divisions,
and with respect to the rain-gauge you
have a similar glass divided into
hundredth-parts of an inch, and all
you have to do is to pour the water
from the bottle into the glass measure.
Notice the divisions the water reaches
up to, and write down the figures, before
the water is thrown away. In making
the entries in your note-book, if less
than one-tenth (.10) inch of rain has
fallen, a cypher must always be pre-
fixed ; thus, if the measure is full up
to the seventh line, it must be entered
as .07, that is, no inches, no tenths, and
seven hundredths. There must always
be two figures to the right of the deci-
mal point. Even in the case of one-
tenth of an inch (usually written .1) a
cypher must be added, making it .10.

Fig. i—The Snowdon Pattern Rain-gauge, as
fixed in the ground in the place of observation.
Neglect of this rule causes much incon-

venience. The unit of measurement
being .01, observers whose gauges are sufficiently delicate to show less than that,
are, if the amount is under .005, to throw it away, if it is .005 to .010 inclusive,
they are to enter it as .01.
Small amounts of water are at times deposited in rain gauges by fog and dew ;
they should be added to the amount of rainfall, because (1) they "tend to water
the earth and nourish the streams;" and not for that reason only, but (2) because
in many cases the rain-gauges can be visited only monthly, and it would then
obviously be impossible to separate the yield of snow, rain, etc.; therefore, for
the sake of uniformity, all must be taken together; and as except by watching all
night it is never possible to be certain that small amounts are wholly dew, it is
best to count all entries of .01 in or upwards as days with rain.
Whenever there is the least doubt respecting the accuracy of any observation, the
entry should be marked with a ?, and the reason stated for its being placed there.
G 2