338 MR. J. HEAP ON THE RAIN-FALL AT OLDHAM. 



XXVI. — On the Rain-fall at Oldham during the years 1836 

 to 1862. By John Heap, Esq. ; with Remarks by G. V. 

 Vernon, Esq., F.R.A.S., M.B.M.S. 



Bead before the Physical and Mathematical Section, April 30th, 1863. 



The observations given in this paper were made at Royton, 

 near Oldham. During the period 1836 to 1852, a 12-inch 

 circular gauge was used, with a float, and situated 24 feet 

 above the ground. From 1853 ^^ ^^57^ ^^^ height was 

 only II feet above the ground. From 1858 to i860, the 

 gauge used was a xo-inch, with float, and 11 feet above 

 the ground. In 1861 and 1862 the float was dispensed 

 with, and the amount of rain fallen estimated by weight, 

 the gauge remaining, as before, 1 1 feet above the ground. 



The mean fall for the first 17 years, 24 feet from the 

 ground, was 32*468 inches. The mean fall for 1 853-1857 

 was 30*802, II feet from the ground. The mean fall, 1858^ 

 to 1862, was 38*069 inches, also 11 feet from the ground. 

 Combining these last two series, we have 34*432 inches 

 for the fall, 1 1 feet above the ground. The corresponding 

 periods at Manchester give, 1836 to 1852, 36*859 inches; 

 1853 *o ^^S7i 31*371 inches; 1858 to 1862, 33757 inches; 

 and 1853 *o 1862, 32*564 inches. 



During the first 1 7 years the fall at Oldham appears to 

 be greatly below that at Manchester ; but this is owing to 

 the elevation of the gauge. The fall during 1858 to 1862 

 would seem to approach nearer the normal fall for Oldham, 

 as compared with the average of the same period for Man- 

 chester, since, the locality being considerably higher, much 

 more rain might ])e expected to fall. If the ratio between 

 the rain-falls at Oldham and Manchester during the period 

 just alluded to held good for the entire period 1836 to 1862, 



