and on the Dip of the magnetic Needle. 395 
I shall subjoin the following Table, by way of elucidating 
what is here mentioned. 
By whom the Variation was observed. 
Mr. Burrows,* * * § in 
Mr, Gunter 
Mr. Gellibrand 
Mr. BoND-f- 
Mr. Gellibrand J 
Dr. Halley § 
Mr. Graham [) 
Dr. Heberden 
Mr. Gilpin 
Year. 
Variation. 
Annual 
Increase. 
1580 
l6'22 
i fi 34 
1 6 57 
1663 
16 j 2 
1692 
1723 
174 8 
1 773 
1787 
1 795 
1802 
1805 
o 
11 
6 
4 
0 
1 
2 
6 
14 
15 E 
o 
6 
o 
22 W 
30 
o 
17 
17 40 
21 9 
23 19 
23 57 
24 6 
24 8 
+ 7,5 
9 . 6 
10,6 
10,2 
9.7 
ib,o 
8.1 
8,4 
9,3 
4.7 
1.2 
°’7 
* The observations of Burrows, Gunter, and Gellibrand’s, in 1634, are 
taken from Seller’s Practical Navigation, 1676. Burrow’s observations are said 
to be the oldest and best in the world ; longitude and latitude found by dipping 
needle, p. xvi. Gellibrand is said :o be the first person who ascertained the 
variation of the variation, about the year 1625, Phil Trans. No. 276 — 278; but if 
this is the date of the observations by which it was determined . the observations of 
Gunter in 1622, show him to have a prior claim ; Bond, in his Longitude found, 
p. 5 and 6, says that the variation was first found to decrease by Mr. John Majr, 
secondly by Mr. Edmund Gunter, thirdly by Mr. Henry Gellibrand, and 
by himself in 1640. 
f Longitude found, p. 3. 
J Ibid. p. 13 ; and Longitude and Latitude found by Dipping Needle, p. 6. 
§ Phil. Trans. No. 195, p. 565. 
jj Ibid. No. 383, p. 107 ; and No. 488, p. 279. 
^ Obligingly communicated by his son, the present Dr. Heberden. 
