102 MEMOIRS?/'//'^ 
Lancajhire and particularly about To-wnky where thefe obfcrva- 
tions were made, is generally efleemed ro have much more rain 
than other parts, it would be unjufl without farther obfervations of 
the like nature in other places, that all England fliould be efii- 
mated to abound as much in rain as thefe parts do : The pounds 
and parts doubled give both the quantity of half pounds, and the 
height in inches 5 with this difference, that for the half pounds, 
only the laft figure is a decimal fraction, and the others the num- 
ber of the half pounds 5 and that for the height, the two laft 
figures denote the decimal fraftion of an inch, and the remainder 
the height in inches, lb near the truth, that they only fall fhort 
of it I inch in 200, which defeat is eafily fupplied ; to this needs 
only be added, that the numbers, on the right hand are the fums 
of all thole in the fame line, that is, in the firil part of feveral 
numbers for ten years 5 fo that the laft of them (hews the fum both 
of the half pounds that have fallen during thatfpace of time, and 
the height the water would have been railed in that lame time ; 
for example, the fum of all the rain m the ten firft years is 
41227, and therefore according to what hath been faid, 412,27 
is the number of half pounds that fell in the compals of the tun- 
nel during thole ten years; and 412,27 the height it would have 
railed the water during that time 3 but if you defire greater ac- 
curancy, add 20(5", its two hundredth part, and you will have 
414,95, for the true height, and 41,493 for the mean height, by 
thefe 10 years obiervations, and 412,27 for the mean quantity of 
half pounds 5 by the lame method you will have the means for 
the other five; viz, of height 41, 78, and 417, 8 for the mean 
number of half pounds, which means do I'urprilingly agree, and 
both conlidered, do give for the mean in all the 15 years 41,515 
inches in height, which is about 7 of an inch more than double 
that at 'Tar is, which is ftated at 19 f French inches, which 
make 2 1 Englifi : Mr. "/ownley's method of gauging by weight 
is grounded on this, that 22,7958 cubical inches of rain-water, 
are equal in weight to i pound, or 12 ounces 'Troy-y lb that di- 
viding any luperfices in inches of a veffel, for receiving the rain- 
water^ by the abovementioned number, it will give the pounds 
and parts that will raife the water on that liirface, with upright 
{ides, juft an inch; and this he found that 4,974 pounds would 
fill a cylinder equal at the bottom to Mr. Townky's tunnel, and 
an inch high, which is nearly 5 pounds, and which will only 
raife the cylinder higher by 3^0 part. 
T'/JO 
