ON THE MAGNETIC INTENSITY OF THE EARTH. 18 
at Paris through the observations at Drontheim, the original 
difference between us at Drontheim pervades the whole series. 
Place. Hansteen. | Sabine. Place, Hansteen. | Sabine. 
PIRATE eke. 0°894 |0°898 || Madeira ......... 1382 |1:373 
Ascension ...... 0:900 |0:920 || Jamaica ......... 1-414 | 1:486 
St. Thomas ...... 0-921 |0-931 || Drontheim ...... 1-430 | 1-442 
Maranham ...... 1:006 |1:016 || Grand Cayman. | 1-480 | 1-454 
Sierra Leone ... | 1:°048 | 1-053 || Havanna..... wee. | 1°493 | 1499 
Gambia River... | 1:129 |1:141 || Hammerfest ... | 1-493 | 1-506 
Port Praya ...... 1-184 |1:193 || Greenland ...... 1:512 | 1:5380 
SEPIA. asec. 1183 | 1:204 || Spitzbergen...... 1531 | 1:562 
Teneriffe ......... 1-300 |1°313 || New York ...... 1:794 | 18038 
In the deductions contained in this table (both in M. Hans- 
teen’s and mine) the dips employed are those which M. Hans- 
teen has calculated from my published observations. The 
differ occasionally a minute or two from my calculated results, 
but in no instance does the difference amount to 3’. 
Liitke, 1826-1829.—These observations were made by 
Captain (since Admiral) Liitke, of the Russian Imperial Navy, 
in a voyage of circumnavigation in H.I.M. ship Siniavin. At the 
request of Capt. Liitke, M. Lenz, of the Imperial Academy of 
Sciences at St. Petersburg, undertook to arrange them for 
publication, and they have since been published in the German 
language in the Memoirs of the Imp. Acad. of Sciences for 1835. 
I was indebted to the friendship of Capt. Liitke for an early 
knowledge of these observations, having received a copy of them 
in a letter from Norfolk Sound in July 1827; but the present 
hotice, as well as the results entered in the table, are taken 
from the published account. 
M. Lenz’s memoir is divided into two sections,—on the ob- 
servations of Dip,—and on those of Intensity. Our present 
purpose is with the latter section. 
-_ The observations of intensity were made with one dipping and 
five horizontal needles. The dipping-needle was 33 inches in 
length, with a steel axle, and was reserved exclusively for mea- 
_ suring the intensity by its vibrations, as there were two other 
_ dipping-needles for observations of the dip. The horizontal 
_ needles were of various shapes, cylindrical, rhomboidal, and 
elliptical, but all of the same length, i.e. two English inches. 
They were obtained in England when the Siniavin was on her 
outward passage. The apparatus in which they were to have 
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