GENERAL SIR EDWARD SABINE ON TERRESTRIAL MAGNETISM. 
357 
bank” at Portsmouth, in 1836 and 1837, 10*23 in British units, which in Professor 
Erman’s Table (Reise, p. 579) has the corresponding value 1*33019 in the scale adopted 
by him. The ratio thus established between Erman’s scale and the corresponding values 
in British units, when carried back to the value assigned in the ‘Reise’ to the Force at 
Kamtschatka (viz. 1*47370, p. 576), shows an amount of loss in the magnetism of the 
needle employed which may well be deemed insignificant in a voyage which lasted an 
entire year, and in which the magnetic instruments were in constant employment. 
I have again to express how greatly these Contributions have been and are indebted to 
the Hydrographer of the Admiralty, Admiral Richards, F.R.S., for his kind permission to 
have the Maps (which accompany this and former Numbers of the Contributions) prepared 
at the Hydrographic Office ; and have again to make my special acknowledgments to 
the Assistant Hydrographer, Captain Frederick John Evans, R.N., F.R.S., for the very 
valuable superintendence which he has kindly given to their preparation and execution. 
Those who are familiar with the records of our early British navigators, the honoured 
predecessors of our modern British Polar Voyagers, will scarcely need to be reminded 
of their Magnetical Observations, bearing testimony to the fact that at that early period 
Inclinations of a much higher value than those which are now observed in the same 
localities prevailed on the coast of Norway, and in the Spitzbergen and Nova-Zembla 
seas. The careful and apparently dependable observations of Henry H udson and others 
in the first years of the 17th century contain the record of systematic observations 
exceeding 80° of Inclination (viz. from 80° to upwards of 86°) in localities where the 
Inclinations are now fully 10° less. It was at that period the frequent practice to 
observe the Inclination at sea on days suitable for the observation, and great attention 
appears to have been given to the subject: no doubt the instruments of those days were 
less precise than modern ones ; but, on the other hand, the very small amount of iron 
then used in the construction of ships must have obviated in great measure the chief diffi- 
culty attaching to more modern magnetic determinations at sea in the higher latitudes. 
There is much to make it probable that the high values of the Inclination which have 
since prevailed on the northern coast of Asia, and are now found on the northern coast 
of America, were then existing on the northern coasts of Europe, and are now adducible 
in evidence of that progress of secular change, with which are also connected the now 
well-established phenomena in the northern parts of Siberia, which I have elsewhere 
ventured to regard as, in part at least, an effect of cosmical influence. 
Lamont . 
ZONE I.— LATITUDE 40° TO 45° N. 
Authorities. 
f Erdmagnetismus sudwestlichen Europa’s (Miinchen, 1858), and Sonnen-Finsterniss in 
1 1860 (Miinchen, 1862). 
Norwegian Officers. . .Hansteen, Mag. Beob. (Christiania, 1863). 
p f Magnetic Survey of the West of France, Philosophical Transactions, 1870; and of the 
1 East of France, Royal Society Proceedings, 1871. 
