Lovering and Bond on Magnetic Observations at Cambridge. 77 
parable. At first sight the two curves with a general agreement 
exhibited some alarming discrepancies ; but these have been referred 
to the stretching of the suspension threads of the new instrument, 
and are not likely to recur again. Another opportunity will be taken 
of comparing the two instruments together after that of Lloyd has 
attained its proper bearings. Fig. 2 of Plate II. represents one hour’s 
observation with these Declination Magnetometers. As the apparatus 
for all the Magnetic Observatories is from the hands of the same 
artist the observations will be eminently comparable. A few years 
of such observations conducted on a systematic and uniform plan 
will avail more in solving the intricate problem of Terrestrial Mag- 
netism and reducing it to a theory, than the whole mass of scatter- 
ed and disorderly data that have accumulated since the days of 
Gilbert. 
