LXVIII PHILOSOPHICAL SOCIETY OF WASHINGTON. 
long; divided by Bird. Phil. Trans., 1785, p. 401, and Measure- 
ment of Lough Foyle Base, p. 73. ’ 
No. 18. Ramsden’s bar, used in the trigonometrical survey of 
Great Britain. Phil. Trans., 1821, p. 91; and Measurement of 
Lough Foyle Base, pp. 73-4. 
No. 14. Sir Geo. Shuckburgh’s scale (1796); a line measure, 
upon a brass bar 1°4 inches broad, 0°42 of an inch thick, and 67-7 
inches long. Space compared, 0 to 36". Phil. Trans., 1798, p. 
133, and Mem. Roy. Ast. Soc., Vol. 9, pp. 84-5. 
No. 15. Ditto. Space compared, 10 to 46". 
No. 16. Ordnance yard 1A (1827); a line measure, upon an 
iron bar 1°45 inches broad, 2°5 inches deep, and rather more than 
3 feet long. Measurement of Lough Foyle Base, pp. 71, 82 and [28]. 
No. 17. Ordnance yard 2A (1827). Similar to 1A. Same 
authorities. 
No. 18. Captain Kater’s Royal Society yard (1831); a line 
measure, upon a brass plate 0°07 of an inch thick. Phil. Trans., 
1831, p. 345. 
No. 19. The Royal Astronomical Society’s standard scale (1834) ; 
a line measure, upon a brass tube 1°12 inches exterior diameter, 
0°74 of an inch interior diameter, and 63 inches long. The central 
yard was the space compared. Mem. Roy. Ast. Soc., Vol. 9, p. 69. 
No. 20. “Col. Lambton’s standard;” a line measure, upon a 
brass plate 0°92 of an inch broad, 0°21 of an inch thick, and 66} 
inches long; strengthened by an edge bar of nearly the same breadth, 
but only 0°08 of an inch thick. Phil. Trans., 1821, p. 88, and Mem. 
Roy. Ast. Soc., Vol. 9, pp. 82-3. 
The authorities for the comparisons given in the various columns 
of the table are as follows: 
Column A.—Comparisons by Mr. George Graham. Phil. Trans., 
17438, pp. 187, and 547-550. 
Column B.—Comparisons by Sir Geo. Shuckburgh. Phil. Trans., 
1798, pp. 167-181. 
Column C.—Comparisons by Capt. Kater. Phil. Trans., 1818, 
p. 55, and 1821, p. 91. 
