Philosophical Transactions. 161 
various branches of physical science, and is illustrated by no 
less than twenty-nine engravings. We shall, as usual, enume- 
rate the papers in the order of their arrangement, giving a more 
or less extensive abstract of each, according to its merits and 
importance. 
1. The Bakerian Lecture. An account of Experiments to determine 
the amount of the Dip of the Magnetic Needle in London, in 
August 1821; wrth Remarks on the Instruments which are 
usually employed in such determinations. By Captain Edward 
Sabine, of the Royal Regiment of Artillery, F.R.S. 
The instruments in general use for ascertaining the dip of the 
magnetic needle, have received little improvement for the last 
fifty years, and are subject to various sources of inaccuracy, 
many of which are without remedy. Convinced, from the trial 
of several needles, that their discordant results were chiefly 
* referable to inaccuracy in the motion of the axis, our author 
requested Mr. Dollond to make a needle on a construction sug- 
gested from similar experience by Professor Mayer, of Gottin- 
gen, but with certain alterations and improvements, which, toge- 
ther with the mode of observation, are described at the outset 
of the paper. The experiments were made in the Nursery 
Garden, inthe Regent’s Park, “a situation far removed from 
the neighbourhood of iron,” and their mean result gives 70° 03’, 
as the mean dip of the needle towards the north, in August and 
September, 1821, within four hours of noon, being the limit 
within which all the experiments were made. Comparing this 
amount with that obtained by Nairne in 1772, and by Cavendish 
in 1776, we obtain 3.02 as a mean annual rate of diminution 
between 1774 and 1821, which is less by 2-5ths than the mean 
annual diminution at Paris, between the years 1798 and 1814, 
as deduced from the observations of Messrs. Humboldt, Gay- 
Lussac, and Arago, whence it might be inferred, if sufficient 
dependance could be placed upon the accuracy of the obser- 
vations, that the annual variation of the dip in this part of 
the world, is greater now than it was forty years ago; yet if we 
take Whiston’s determination of the dip in 1720, 75° 10’, we 
obtain, between the years 1720 and 1724, an annual diminution 
of 3'.05, which almost exactly coincides with the rate now 
found for the succeeding forty-seven years. 
2. Some Positions respecting the Influence of the Voltaic Battery, in 
obviating the effects of the division of the Eighth Pair of Nerves. 
Drawn up by A. P. Wilson Philip, M.D., F.R.S., Edinburgh. 
‘Communicated by B. C. Brodie, Esq., F.R.S. 
Our high opinion of the importance of Dr. Wilson Philip’s 
physiological researches may be judged of, by the space which 
we frequently devote to them in this Journal. The short paper 
