ae 
fe 5: 
7 
. i, 
364 H. C. RUSSELL. 
defect of rainfall from ten to twenty-five per cent., either sign 
enclosed by a ring quantities over twenty-five per cent. The same 
author in 1884 made a diagram in which the length of a vertical 
line shows the quantity of rain in each month, and twelve such 
lines placed side by side show the rainfall for the year for each 
district in which they are placed. The Meteorological Office of 
the United States draws on some rain maps lines of equal rainfall 
in addition to the shading, which define more clearly the limit 
over which the same quantity has fallen. 
Third, those in which the quantity of rain is shown by actual 
figures located so that they indicate the rainfall for the district 
in which they are placed. One of the first of these, if not the 
first, forms part of the report on the Meteorology of the Bombay 
Presidency for 1878, and shows the rainfall there for 1874 and 
previous years. In this the country is divided by red lines into 
small areas, in which each individual record is given in black ink, 
and the mean of all is given in red ink, but the effect is not pleas- 
ing and the information not rapidly assimilated. In New South 
Wales we first used this method in 1883 to indicate the mean 
rainfall over this colony. ‘The figures were large and can be read 
at a distance of six or eight feet, the object being to make it 
possible to see the quantities easily, and they are so conspicuous 
that they remain as a mental picture not easily forgotten. At 
that time observers were not so numerous as they are to-day, and 
for considerable areas there were no observers, the number has 
gradually increased and is now more than twelve hundred ; and 
in the new edition of the 1883 map, which I have brought to 
exhibit to-night, we have been able to get several stations in each 
square degree of the Colony, save one exception in the extreme 
north-west. The mean of the records in each square degree has 
been taken as the average rainfall for that area, and this quantity 
is shown to the nearest quarter of an inch in large figures on the 
degree, while other smaller figures show the number of years over 
which the observations have extended, and the number of stations 
used to find the mean. 
