Oct. 14, 1886] 
NATURE 
SAS 
time ball, also, was not fit to drop the ball, the blow of 
the hammer failing to discharge the bolt, so that the 
hammer had also to be struck at the instant the current 
arrived from the clock. The coil was fused by lightning 
on June 12, and from that date until November 20, the 
ball was dropped by hand. Since November 22 a new 
lock has been fitted, which gives satisfaction. 
The time-ball tower is erected on Tsim-sha-tsui Point, 
directly facing the shipping. It stands in front of the 
new police-station beside the mast for hoisting meteoro- 
logical signals, at the foot of which the typhoon gun, 
pointed towards the city opposite, is placed. In the 
police boat-basin, at a short distance north-west of the 
tower, the small observatory is built. The time-ball 
tower is about half a mile distant from the observatory, 
with which it is connected by wire. The base of the 
tower is about 4o feet above sea-level, and the top of the 
ball-mast about 84 feet. On the ground-floor is a massive 
granite pier, which supports the entire apparatus. Dr. 
Doberck describes at considerable length the arrange- 
ments for dropping the ball, for breaking its fall, and for 
ascertaining that the fall has taken place at the proper 
instant, but they do not call for special remark. The 
accuracy of the time-ball signal at 1 o’clock depends, he 
says, practically upon the error of the standard clock 
being accurately determined. If the weather has per- 
mitted transit observations to be made the previous 
evening, the error of course will be pretty closely known ; 
otherwise the regularity of the rate of the standard clock 
must be trusted to. A table of the errors of the time-ball 
in 1885 is given, showing that the mean probable error of 
the signal for each month is about o°2s. 
The time service is at present confined to the dropping 
of this ball, but there would be, Dr. Doberck points out, 
no difficulty in dropping any number of time-balls along 
the coast or distributing hourly time-signals to the prin- 
cipal public buildings, &c. 
The observatory possesses three chronometers, the 
rates of which are here given. Of the three, two keep 
mean-time, and one keeps sidereal time, but one of the 
former is useful only as a hack watch. 
The equatorial of the observatory is the Lee equatorial, 
described by Admiral Smyth in the “Speculum Hart- 
wellianum”’ and the “ Celestial Cycle.” The great length 
of the polar axis renders the instrument unsteady and 
sensitive to every motion of the observer. A Maclean 
star spectroscope has been fitted to it. The object-glass 
appears to be still in good condition. 
The meteor shower (the Andromedes) of November 27 
was observed, and it was estimated that about 2009 
meteors an hour were visible, most being small; none 
being brighter than the first magnitude, and only a few 
so bright. The radiant was determined to be at R.A. 27°, 
Decl. 40° N., but it was at least 3° in diameter. 
THE RAINFALL OF THE CAPE COLONY 
BSERVATIONS of rainfall were begun in the 
colony about forty-five years ago, but until 1876 no 
general system of registration was in force ; and, except 
in the case of the Royal Observatory and a few other 
stations, no continuous records were available. In 1876, 
however, Mr. John G. Gamble, M.A., M.Inst.C.E., the 
Hydraulic Engineer to the Colony, induced the Govern- 
ment to grant a sum of 100/. for the purpose of establish- 
ing rain-gauges throughout the country. This grant has 
been continued yearly since then, with the result that, 
although the sum is quite inadequate for the speedy 
erection of the number required, there are now 250 
gauges from which monthly returns are obtained. <A 
gauge is placed at every seat of magistracy, and private 
persons are also supplied with gauges free of charge on 
condition that they observe continuously for five years, 
and forward monthly returns to the Meteorological Com- 
mission at Cape Town. All the services rendered by the 
observers are gratuitous. The monthly returns are tabu- 
lated and printed together with other meteorological 
observations in a report by the Meteorological Com- 
mission, which is presented annually to the Colonial 
Legislature. 
At the end of 1883 there were 75 stations at which 
records had been kept for at least five years. An ap- 
pendix showing the average rainfall for each month of 
the year at these stations was published by the Meteoro- 
logical Commission in their 1883 report, and in their 
report of the following year some diagrams plotted from 
these averages were included, which show more strik- 
ingly than figures the fluctuation of the rainfall from 
month to month. 
That the observations begun ten years ago are be- 
ginning to bear good fruit is evident from the series of 
rainfall maps exhibited in the Court devoted to the Cape 
of Good Hope at the Colonial and Indian Exhibition. 
There are sixteen maps altogether, fourteen of which 
have been compiled by Mr. Gamble and two by Mr. W. 
B. Tripp, F.R.Met.Soc. One of those by Mr. Gamble 
shows the position of the gauges and the districts into 
which the colony has been divided for the purpose of 
rainfall registration ; the others represent, by means of 
different colours, the general distribution of rainfall for 
each month of the year and for the whole year. The 
contours on the maps for the various months show 
differences of r inch in the rainfall, starting from a 
contour indicating the area where the fall is less than 
o5inch. The contours on the map for the year indicate 
differences of 12 inches, beginning at 6 inches, and going 
up to 54 inches. The number of inches of rainfall at the 
various places is marked in figures. 
Mr. Tripp’s maps are intended to show the relation 
between the physical configuration of the country and its 
rainfall—one map representing contour-levels every 1000 
feet up to 4000 feet, and the other representing the mean 
annual rainfall. 
A casual examination of the various maps is sufficient 
to show that the conditions which determine the rainfall 
are not the same for the whole of South Africa. Thus 
in the south-west district of the Western Province the 
chief portion of the rain falls in the winter months, while 
in the Eastern Province, and in Natal and the Orange 
Free State, the greater portion falls in the summer, frorn 
October to March. On the southern seaboard of the 
Cape Colony the rainfall is irregularly distributed through- 
out the year, the greatest monthly fall at any place vary- 
ing from one-ninth to one-eighth of the total. 
A glance at Mr. Gamble’s map showing the distribu- 
tion in the year, shows that the north-west part of the 
colony is almost rainless. With the exception of the 
tract occupied by the Namaqualand Mountains, the 
average yearly fall in this desert is less than 6 inches ; at 
Pella, a village on the Orange River, the rainfall for the 
year is 23 inches, one-fifth of which falls in May. Some 
of the months at this place are rainless. Throughout the 
greater part of the colony the yearly rainfall varies from 
6 to 18 inches, the smaller falls being characteristic of the 
regions in the interior, generally known as “ The Karroo,” 
from 2000 to 4000 feet above sea-level, and of a plateau 
nature; while the greater falls are found nearer the sea, 
and in the mountainous parts. In the south-west district, 
excluding the Cape Peninsula, and on the narrow strip of 
country on the south coast, between Swellendam and 
Port Elizabeth, the yearly rainfall ranges from 18 to 30 
inches, except in the forests of George and Knysna, 
where it exceeds 4o inches. In the Cape Peninsula the 
rainfall varies from 25 inches at the Royal Observatory 
to 54 inches on the south-east side of Table Mountain. 
In the eastern districts of the colony, and in the neigh- 
bouring territories, where the main portion of the rain 
comes in summer, the fall averages from 18 to 30 inches, 
