884 



REPORT — 1869. 



it is well to try 



Fig. 1. 



For the sake of clearness, it lias been found necessary to lay down an inva- 

 riable rule that there shall always be two figures to the right of the decimal 

 point. If there be only one figure, as in the case of one-tenth of an inch 

 (usually written •!), a cipher must be added, making it "10. Neglect of this 

 rule causes much inconvenience. All columns should be cast up tivice. 

 When there is no rain, a line should be drawn rather than ciphers inserted. 



XI. Caution. — The amount should always be written down before the 

 water is thrown away. 



XII. Small Quantities. — The unit of measurement being -01, observers 

 whose gauges are sufficiently delicate to show less than that, are, if the 

 amount is under -00.5, to throw it away; if it is "005 to -010 inclusive, they 

 are to enter it as "01. 



XIII. Every observer should train some one as an assistant ; but where 

 this is not possible, instructions should be given that the gauge should be 

 emptied at 9 a.m. on the 1st of the month, and the water bottled, labelled, 

 and tightly corked, to await the observer's return. 



XIV. Heavy Eains. — ^When very heavy rains occur, it is desirable to 

 measure immediately on their termination ; and it wUl be found a safe plan, 

 after measuring to return the water to the gauge, so that the morning regis- 

 tration will not be interfered with. Of course if there is the slightest doubt 

 as to the gauge holding all that falls, it must be emptied, the amount being, 

 in accordance with Rule XI., pi-eviously written down. 



XV. Snow. — In snow three methods may be adopted ; 

 them aU. (1) Melt what is caught in the funnel, and 

 measure that as rain. (2) Select a place where the snow 

 has not drifted, invert the funnel, and turning it round, 

 lift and melt what is enclosed. (3) Measure with a rule 

 the average depth of snow, and take one-twelfth as the 

 equivalent of water. Some observers use in snowy wea- 

 ther a cyliuder of the same diameter as the rain-gauge, 

 and of considerable depth. If the wind is at all rough, 

 aU the snow is blown out of a flat-funnelled rain-gauge. 



The desirability of more accurate information of the 

 maximum fall of rain in the minimum time has recently 

 beeu strongly felt. It wiU be supplied by the use of the 

 instrument shown in figure 1. Its principle is very sim- 

 ple, consisting merely in the employment of a collecting 

 area about twenty times that of the measuring-tube ; an 

 iuch of rain is therefore expanded to a length of nearly 

 2 feet, and the rising rain-water in the tube carries on its 

 surface a small white glass baU which renders the reading 

 of the gauge visible from a considerable distance ; an 

 overflow pipe is also provided, by which the measurement 

 is continued up to 2 inches. 



In the year 1863 Mr. Symons read a short paper before 

 the Mathematical Section of this Association, at the New- 

 castle-upon-Tyne Meeting, wherein he briefly notified the 

 inauguration of the now weU-known Calne rain-gauge experiments. The 

 observations having been stopped in the year 1868, in consequence of the re- 

 moval of Colonel Ward from Calne, considerable attention has been given to 

 the discussion of the very voluminous record sheets. Those connected with 

 the A-ariation in the amount of raiu collected at various heights above the 

 grouud are in the hands of the Rev. J. M. Du Port, M.A., for examination. 



