53 
The following were the bases measured : 
Feet 
I. Base on the Moy plain flat meadow, subject to ita 800 
in the barony of Gallen : f pee 
2. Base on the plain at the head of Lough Carra, in the 
barony of Carra, meadow and bottom t oP 
3. Base on the sands of Killala, in the barony of Ty- 
} 9500 
rawley : . 
4. Base on the sands between the island of Reina chee 9971.9 
Inishbegit, in the half barony of Erris ; 
5. Base on the sands of Bertragh, barony of Murrisk 4545 
6. Base in the barony of Costello, along a flat bog road 8600 
7. Base over the ice, when the lake of Castlebar was frozen in the 
Barony of Carra, 11097.4 feet, and which was rendered of no use, 
as some idle person had destroyed the mark, which terminated the 
length of the base. I would recommend in all similar operations 
double marks within a few feet of each extremity. The bases were 
all measured twice. In repeating the measurements with Mr. 
Troughton’s chain, I always observed that the lengths measured 
during the warm part of the day were minus when compared with 
the same lengths taken in the evening, when the cold had com- 
menced. The thermometers always afforded an accurate correction. 
All the bases, with the exception of the one over the ice, were mea- 
sured during the warm part of the summer; the corrections were 
small. In measuring over the ice of Castlebar lake in January 
1814, Farenheit’s thermometer stood at a mean of 29°; the tempe- 
rature, when the chain had its terminating lines laid off from the 
British brass standard in the Tower of London, was 65°. of Faren- 
heit’s thermometer ; this is a difference of 36%. and using the data 
given by Mr. Troughton, we shall have the following results : 
L 2 
