Royal Physical Society. 19 



Fleming remarked that the expensive forms in which rain-gauges were 

 usually constructed, making their price range from two to four guineas, 

 rendered these instruments comparatively rare. The gauge which he re- 

 commended and exhibited to the Royal Society of Edinburgh, 16th April 

 1849, was fully described in the Edinburgh New Philosophical Journal 

 for July following. In its most expensive form, and made of copper, by 

 Mr James Bryson, optician, Princes Street, it will cost about L.l. Its 

 price, however, could be reduced one-half, or even three-fourths, by con- 

 structing it of sheet zinc or common tinplate. The position of rain- 

 gauges was next adverted to by the Professor, who stated, that visiting 

 the Isle of Glass, in the Hebrides in 1821, and questioning Mr Reid, the 

 keeper of the lighthouse, as to the working of a rain-gauge which had re- 

 cently been erected, according to the form used at the other stations, he 

 was assured that its indications were trustworthy in calm weather ; but 

 during rain with wind, his boat in the neighbourhood was often filled with 

 water, while the gauge remained nearly empty, adding that the rain- 

 drops which at such a time fell into the funnel were swept out again by 

 the eddy wind. Reflecting on this circumstance, and others of a similar 

 kind, Professor Fleming became convinced that rain-gauges placed on the 

 tops of houses, or even a few feet above the surface of the ground, were 

 comparatively useless. The late Mr Thorn of Ascog, in Bute, arrived at 

 the same conclusion, so that the gauges which he employed in estimating 

 the quantity of available water for mill-dams were sunk into the ground in 

 a grass plot, the mouth of the funnel being nearly level with the surface. In 

 this position the disturbing influence of the wind is removed, while the 

 equable temperature of the ground prevents the evaporation in the cylindri- 

 cal receiver. The rain-gauges employed at the lighthouses "are elevated 

 4J feet above the ground ;" and Mr Thomas Stevenson, C.E., having 

 issued queries to the keepers, received, among others of a similar kind, 

 the following answers: — "Lighthouse, Inchkeith. — When the wind is 

 high, no snow and very little rain goes into it." " Buchanness.— When 

 there is little or no wind, it is pretty near the truth ; the more wind, the 

 further from the truth." The gauges referred to by Dr Miller in his 

 paper on the Meteorology of the English Lake District (Ed. Trans, xxi., 

 p. 81) appear to be placed two feet above the ground, and are thus ob- 

 jectionable in their position, and the accuracy of the indications doubtful. 

 The author stated as the result of experiment, in accordance with theo- 

 retical considerations, that rain-gauges need not exceed three inches in 

 diameter, that the trouble attending them may be limited to emptying 

 them once-a-month, and that the index rod, if divided into tenths of an 

 inch, is sufficient for all practical purposes. The eye with a very little 

 practice can easily read off to one-fourth of a tenth, a difference often 

 greater than the amount of rain falling at the same time within short 

 distances. He mentioned that gauges of the description which he had re- 

 commended were being established in different parts of the country. 

 Twelve parish schools in Annandale were furnished with them by Mr 



