272 THE NATURAL HISTORY 



being filled again twice at Newton, the mercury stood, on 

 account of the great elevation of that house, three-tenths 

 of an inch lower than the barometers at this village, and 

 so continues to do, be the weight of the atmosphere what 

 it may. The plate of the barometer at Newton is figured 

 as low as 27 ; because in stormy weather the mercury 

 there will sometimes descend below 28. We have 

 supposed Newton-house to stand two hundred feet higher 

 than this house : but if the rule holds good, which says 

 that mercury in a barometer sinks one-tenth of an inch 

 for every hundred feet elevation, then the Newton 

 barometer, by standing three-tenths lower than that of 

 Selborne, proves that Newton-house must be three 

 hundred feet higher than that in which I am writing, 

 instead of two hundred. 



It may not be impertinent to add, that the barometers 

 at Selborne stand three-tenths of an inch lower than the 

 barometers at South Lambeth ; whence we may conclude 

 that the former place is about three hundred feet higher 

 than the latter ; and with good reason, because the 

 streams that rise with us run into the Thames at Wey- 

 bridge, and so to London. Of course therefore there 

 must be lower ground all the way from Selborne to South 

 Lambeth ; the distance between which, all the windings 

 and indentings of the streams considered, cannot be less 

 than an hundred miles. 



I am, etc. 



LETTER LXI 



Since the weather of a district is undoubtedly part of its 

 natural history, I shall make no further apology for the 

 .four following letters, which will contain many particulars 



