184 Dr Fleming on a Simple Form of Rain-Gauge. 



on the free surface, which had been uniformly I'etarded on 

 the grass plot, and consequently receives a fair proportion of 

 the falling rain. 



The body of the gauge, for receiving the water collected 

 by the mouth or funnel, by being placed in the ground, is 

 protected against changes of temperature ; little or no evapo- 

 ration can take place, so that the emptying and adjusting 

 may be effected at distant intervals. 



Having employed for several years, at Abei'deen, an instru- 

 ment presented to me by Mr Thom, I was satisfied that it 

 fulfilled neai'ly all the conditions of a trustworthy instru- 

 ment, differing, however, in its humble appearance, from those 

 eye-traps or gimcracks usually set up as rain-gauges. The 

 process of emptying, however, was a troublesome one, as the 

 funnel required to be removed, tlie float lifted out, and then 

 the water in the cylinder taken up by means of a cup or 

 sponge, at the end of every month or two, according to cir- 

 cumstances. 



To remedy this evil, it occurred to me, that by employing 

 an external cylinder, permanently placed in the ground, for 

 receiving the cylinder forming the rain-gauge, a consider- 

 able improvement might be effected. 1. The necessity of 

 removing the funnel at every adjustment, might be got rid 

 of by having a stopcock at the bottom of the receiver, so that 

 upon the gauge being lifted out of the ground, or rather out 

 of its external case, the water might, without trouble, be let 

 off, and the float adjusted to zero, by the addition of the re- 

 quisite quantity of water by the mouth of the instrument. 

 2. By getting quit of the funnel, the whole gauge may be a 

 single cylinder, with the mouth of the same diameter as the 

 body of the instrument, whereby errors of workmanship, pro- 

 ducing unequal areas, may be avoided. 3. By simplifying the 

 instrument, and thereby greatly reducing the expense, it is 

 expected that observers will be increased, and additional data 

 procured for determining the distribution of rain over the 

 globe, by details furnished by comparable gauges. 



The preceding remarks will render any minute description 

 of the instrument unnecessary, but the following notices may 

 be of use. 



