ON THE MAGNETIC INTENSITY QF THE EARTH. 33 
inconsiderable amount, admitting of safe and easy interpola- 
tion. 
Capt. Fitz Roy’s observations are not yet published. On his 
return to England he paid me the compliment of placing them 
in my hands to calculate and arrange for publication in the 
appendix of an account of his voyage, which he is preparing. 
Meanwhile he has permitted me to insert the intensity results in 
the general table of this memoir. They are corrected for tem- 
perature and for arc. They include 27 stations, of which 24 
in the southern hemisphere, distributed throughout its longi- 
_ tudes, throw very considerable light on the system of the inten- 
sity inthose regions. This extensive series is, I trust, but the 
precursor of what British naval officers will accomplish for mag- 
netism in the southern hemisphere. 
Rudberg, 1832.—These observations were made with a dip- 
ping-needle and two horizontal needles of Gambey’s, at five 
stations on the continent of Europe, of which Paris was one. 
A full account of them is published in the xxviith vol. of the 
Annalen der Physik. They appear to have been made with 
great care, and the results are corrected for temperature. 
Lloyd and Sabine, 1835-1836.—These observations were 
made in compliance with a wish expressed by the British Asso- 
ciation that some of its members would undertake a survey of 
the dip and intensity in the British Islands. Accordingly the 
intensity was determined at 80 stations in Ireland by Mr. Lloyd 
and myself, in 1835, and by myself at 25 stations in Scotland, 
in 1836. 'The volumes of the Reports ofthe British Association 
for those years contain a full account of these observations, as 
well as of the mode in which the determinations at the several 
stations are all made to concur in assigning the intensity at 
one central position in each country as their general result. 
It appears unnecessary, therefore, to reprint them in this 
yolume, and it is only the intensities at the central position, 
thus calculated, which are entered in the general table. 
Ross, 1836.—These observations were made in a voyage to 
‘ ‘Davis’s Straits, undertaken by Capt. James Ross, R.N., in 
_ the winter of 1836, to relieve the crews of several whalers 
_ which had been detained in the ice. Those of the intensity 
_ were made with two horizontal needles in an apparatus similar 
_ to M. Hansteen’s. The magnetism of one remained quite 
_ steady during the voyage; the other sustained a slight loss, 
which it is evident by inspection took place between Orkney 
VOL. vi. 1837, D 
