Mr James Straton on the Rain- Gauge. 41 



From what has been said, it appears that from 14 to 18 

 inches above the snrface of the soil is a proper position for 

 the mouth of the receiver of the rain-gauge, (1.) because there 

 the rain-drops have received their proper additions from the 

 atmosphere ; (2.) because there they have received no addition 

 from the surface of the ground ; but (3.), and chiefly, because 

 the most suitable form of gauge, for accuracy in practice, has, 

 when so planted, about 20 inches of its cistern or stem below 

 the surface of the ground, and being thereby placed beyond 

 the influence of all the ordinary, and most of the extraordinary 

 vicissitudes of temperature, is protected from evaporation 

 by heat in summer, and destruction by frost in winter. Mr 

 Thorn's rain-gauge, used and described by Dr Fleming, is a 

 cylinder immersed to the surface-level of the ground; and he 

 frequently told me that, during the warmest and least rainy 

 months of summer, he never detected any perceptible dimi- 

 nution of the water in the gauge from evaporation. As this 

 is quite consistent with my own experience, I leave the point 

 as settled ; but the frost in winter is the inveterate enemy, 

 the insuperable barrier, indeed, to the general and con- 

 stant use of the rain-gauge as it is usually made and planted. 



Few observers are willing to empty their gauges habi- 

 tually more frequently than once or twice a month. During 

 the course of my experiments, some eight or nine instruments 

 were planted by different observers in and about the locality 

 but one after another they have all disappeared. They were 

 made, some of copper, some of zinc, others of iron or tinplate. 

 They were each enclosed in a wooden case, and the whole 

 instrument was above ground, from three to five feet being 

 the favourite height for the mouth of the receiver. Almost 

 every night that a smart frost set in after rain, when the 

 gauge contained water, it was frozen, and the metal gene- 

 rally burst, as a matter of course. The observers persevered 

 in repairs day after day, winter after winter, till wearied out, 

 sooner or later, the repair was left undone, the gauge was 

 useless, neglected, and became a wreck. 



I have never yet seen or heard of an instance of freezing 

 in one of my gauges, some of which have been in constant 

 use for six, seven, and eight years. It is quite possible to 



