66 
Brmarlis on the recent Conference at Vienna on 
is the careful entry of each occurrence of dew. It is recommended to conduct 
investigations for the purpose of devising a satisfactory dew gauge. 
"As to fogs, the general rules proposed by the Vienna Meteorological 
Congress in 1873 should be followed." 
The question of dew measurement is very interesting, but 
difficult. The total amount of moisture returned to the earth as 
dew has been estimated by Mr. G. Dines, F.M.S., as not above 
1'5 inches annually. 
The idea that the so-called dew-ponds are really filled by 
dew has been satisfactorily disposed of by Mr. H. P. Slade 
in his pamphlet on the subject, published by Spon in 1877.* 
The only rule about the entry of fogs which was laid down 
by the Vienna Congress, is that fog should not be reported 
unless the observer was really enveloped in it. 
R. 16. " The observations on rain, for objects connected with agricultural 
meteorology, should be conducted on the principles laid down by the Vienna 
Congress. 
" It is very important for the purposes of agricultural meteorology that as 
large a number as possible of stations of a simjile kind should be established, 
at which observations only of thunder-storms and of rain should be taken." 
E. 17. " For the measurement of snow, gauges should be provided, which 
will prevent the danger of snow being blown out of the receivers." 
It is hardly necessary to insist on the importance of rain 
observations in these islands, where the British rainfall system, 
under Mr. Symons, numbers some 2000 stations. As regards 
snow-gauges, the deep cylinders placed on top of the receiving- 
funnels of the gauge used by the Meteorological Office meet 
the requirements of the resolution. 
R. 18. " Observations on the percolation and evaporation of the water in the 
soil should be introduced into the system of observations in connection with 
agricultural meteorology, but on no account are Lysimeters to be used. 
" (The methods recently employed by Prof. Ebermayer in Bavaria have 
been described by him in an Appendix to the Report of the Conference)." 
The Lysimeter consists of a metallic cylinder sunk in the 
ground and filled with earth. There is a double bottom, and 
a pipe leads from the apparatus to collect the water which 
percolates through the earth into the cylinder. 
The section of the cylinder is one square foot, and it is made 
of various depths from one to four feet. The experience gained 
at the forest stations in Bavaria shows that the percolation 
determined by such a gauge is not correct. The earth at the 
bottom of the cylinder is always damper than the natural earth 
* ' A small practical Treatise on Dew Ponds, the Farmer's Summer Water 
Supplies; being invaluable on hilly farms and sheep-rnns, self-supporting, need 
no repair, and always efficient.' By Harry Pool Slade, Blewberton House, 
Aston, Wallingt'ord, Berks. London : E. and F. N. Spon, 48, Charing-cross. 
1877. 
