REPORT ON THE METEOROLOGICAL OBSERVATIONS. 393 
receiver should at any time prove too small for any exceptionally heavy 
downpom% or in case the receiver be broken by frost. The gauge is 
securely fixed in the ground, with the top of the rim 1 foot above the 
general level of the enclosure. This gauge has been tested by the late 
Mr. G. J. Symons, F.R.S., and has received from him a certificate of 
accuracy. 
The Time of Observation. — The observations are made regularly at 
9 A.M., and at that hour the self-registering thermometers are set. All 
the readings are entered against the date on which they are made, except 
those of the maximum thermometer and the rain-gauge, which are put 
down to the previous day. The students at the Gardens take the 
observations each month in turn, under the supervision of the regular 
observer, Mr. T. W. Turner. 
Fig. 140. — Meteorological Station at Chiswick. 
Thermometer on Post. — In addition to the standard instruments a maxi- 
mum and minimum Six's thermometer has been mounted on the north side 
of a post 3 inches square. In order to prevent the sun from shining 
upon the instrument at any period of the year it is protected at the sides 
by two flanges of wood, 4^ inches deep by 16 inches long, in such a way 
that they project 1^ inch beyond the north side of the post ; and above 
Dy means of a sloping piece of zinc. The readings .of this thermometer 
can only be regarded as sufficiently close approximations to the true air 
temperature for ordinary garden observations. For such a purpose 
this plan of exposing a Six's thermometer can be recommended as a 
very simple and inexpensive one. The instrument now in use has 
not a sufficiently open scale, and will be shortly replaced by a larger 
