440 REPORTS ON THE STATE OP SCIENCE. — 1919. 



for any other meteorological element. Moreover, the records which are of the 

 greatest scientific value a.re frequently those made in sparsely inhabited regions ; 

 it is therefore often necessary to depend upon the assistance of uneducated, 

 and sometimes illiterate, observers. The process of observing must therefore 

 be reduced to its simplest terms, and instruments must be devised as far 

 as possible 'fool-proof,' and free from all complication. 



The evolution of the standard rain gauge as we now know it ^ was a slow 

 and laborious piece of work. The several long series of elaborate experiments 

 conducted at the inspiration, and under the guidance, of the late Mr. G. J. 

 Symons, F.R.S., and described in the earlier volumes nf British Rainfall, bear 

 eloquent testimony to the care and labour expended on the subject. The reasons 

 for the rejection of non-standard types of rain gauge are cogently set forth 

 by Dr. H. R. Mill in his paper, ' The Best Form of Rain Gauge, with Notes 

 on other forms' {Q.J.B. Met. 'Soc, vol. xxxiii., 1907, pp. 265-272), and it is 

 not necessary to recapitulate them afresh. 



Whilst by no means assuming that the last word has been said on the subject 

 of improving the standard rain gauge, it is a matter of great interest to note 

 that observations made by means of this gauge in nearly every instance satisfy 

 the extremely severe tests imposed by Dr. Mill's cartographic methods of 

 working with rainfall records in a, far more satisfactory manner than do those 

 deriVied from non-standard gauges. The.se tests have been so extremely 

 nmuerous and so unmistakably conclusive that the question of the superiority 

 of the standard gauge over other patterns up to the present devised may be 

 regarded as settled. 



The adoption of the standard rain gauge marked an important step in the 

 solution of the problem of accurate rainfall recording, and its substitution 

 for obsolete forms has steadily progressed during the last fifty years, but the 

 fact that by far the majority of rainfall observers in this country are voluntary, 

 and equip themselves, makes it impossible to ensure the entire suppression of in- 

 ferior patterns. Unfortunately, the comparative simplicity of construction of a 

 rain gauge induces certain makers, with no interests beyond the sale of their 

 goods, to continue to put on the market gauges of undesirable patterns, sometimes 

 inaccurately graduated, and these are often purchased in good faith by the 

 uninstructed on the word of a salesman that they are ' of the usual kind.' 

 It is necessary continually to counteract this tendency by the free issue of 

 the pamphlet, ' Rules for Rainfall Observers,' describinsr the approved gauge, 

 where it can be obtained, and the methods of using it. The issue of certificates 

 of accuracy in respect of non-standard gauges has been discontinued. 



The adoption of the standard hour (9 h. G.M.T.) for the observation of 

 rainfall was another of the organizing triumphs of Mr. Symons. The difficulty 

 lay less in the selection of a convenient hour than in the task of bringing about 

 the nearly complete uniformity of practice which was secured, bearing in mind 

 that it was, and still is, impossible to insist upon compliance in the vast majority 

 of cases. The imquestioning acceptance of advice on this point has been of 

 immense assistance in simplifying the study of daily rainfall, it being now 

 possible to plot several thousand daily records on a map in complete confidence 

 as to the identity of the period imder observation in all but a small number of 

 instances, which as a rule declare themselves at once. During the last few 

 years this uniformity has been to some extent marred by the introduction of 

 ' summer-time.' 



The satisfactory outcome of the adoption of luiiform instruments, methods, 

 and hours by so large a proportion of the corps of 5,000 observers now at work 

 in the British Isles, removes some of the most serious difficulties which confronted 

 those who first set themselves to study the subject, or rather reduces these 

 difficulties to comparatively manageable proportions. It is still necessary con- 

 tinually to urge more complete imiformity, and every approximation towards 

 this end improves the utility of the observations as a whole. 



2 The standard rain gauge is at present made in three principal patterns — 

 the Meteorological Office pattern, the ' Snowdon,' and the 'Bradford '■ — differing 

 essentially only in the size of the funnel and in capacity. A common feature 

 is the vertical rim above the funnel. 



