414 Transactions of the South African Philosophical Society. 



other rain-gauge, fitting into its opening by means of a narrow 

 socket. Four wires attached at opposite sides, and fastened to 

 stones near by, protected the frame against the fury of the wind. I 

 had consequently one ordinary gauge and one with an imitation 

 bundle of reeds 1 foot high." 



Further on we are informed that the observations came to an 

 untimely end on the 15th of February, the gauges being destroyed 

 the week after. 



In order to understand what follows it is necessary to make the 

 following remarks on rainfall-measurement in general. 



The object of rainfall-measurement is to ascertain as accu- 

 rately as possible the depth in inches of the water which would 

 accumulate on a level surface if the rain were to remain where 

 it fell. 



To enable this to be done, the rain is collected in a specially- 

 constructed vessel, called a rain-gauge, of known area, and the 

 amount is measured off by means of a graduated measure which 

 shows true inches and fractions of an inch, corresponding to the 

 receiving-area of the gauge. One of the chief points to be attended 

 to by rainfall observers is that the area is not altered in any way, 

 otherwise the graduated measure will indicate erroneous quantities, 

 and the results will be worthless. Eain gauges are generally circular 

 in shape, and as a circle encloses the greatest area of all closed 

 curves of the same perimeter, the smallest indentation or squeezing 

 in of the rim of the funnel must make the rainfall indicated too little 

 in amount. Conversely, if by any means whatever the receiving- 

 area is artificially increased, the measure will indicate quantities 

 which are too large. 



Now in the case of the rain-gauge with the framework containing 

 the reeds, used by Dr. Marloth, we have not only the actual hori- 

 zontal area of the five-inch rain-gauge collecting the moisture, but 

 the whole of that part of the superstructure above the lower ring is 

 capable of catching moisture, and being so constructed as to drain 

 into the gauge, thus adds its quota to that which would be caught 

 under ordinary circumstances by the plain open rain-gauge. It 

 will therefore be seen that the catcliment area has been increased 

 in the case of Dr. Marloth's second rain-gauge by an amount 

 depending on the area of that part of the superstructure already 

 indicated. 



Through the courtesy of Dr. Marloth I have been able to closely 

 examine tlie apparatus used, which was but roughly constructed, 

 and defies accurate measurement. However, the following figures, 

 which were obtained by using a pair of compasses as callipers, and 



