^8S Prof. Barlow’s Experiments for determinmg the 
To establish a perfect synonymy between so many authors, 
would be of so much advantage to geologists, that some scienti- 
fic society ought to propose such an attempt as the subject of a 
prize. 
Art. X. — An Account of a Series of Experiments, made to de- 
termine the Local Attraction of his Majestfs Steam-Vessel 
Comet By P. Barlow, Esq. F. R. S., Professor Royal Mi- 
litary Academy. 
No experiments having yet been made on the local attraction 
of a steam-vessel, and the iron in these cases being very differ- 
ently distributed to what it is in vessels of the usual con- 
struction ; and, moreover, as the above steam-boat was going 
down the coast of Norway for certain observations connected 
with the determination of the longitude, &c. it was thought de- 
sirable to ascertain the effect of her iron-works on the compass 
before she left the River ; and I therefore received directions 
from my Lords Commissioners of the Admiralty, and from the 
Navy Board, to take with me the six gentlemen who had been 
ordered to attend me for instruction *, and make such observa- 
tions and experiments as might seem desirable in this novel 
case. 
I had been before requested to give my opinion as to the pro- 
bable effect which the projected hollow iron-masts in men-of- 
war might have on the compass ; and I stated, that I thought it 
probable so great a surface carried above the deck would have a 
counteracting effect on the usual iron of the vessel, by bringing 
the common centre of attraction of all the iron nearly into a ho- 
rizontal plane with the compass, and therefore, in these latitudes, 
nearly into the plane of no attraction, so as to leave it doubtful 
whether the actual effect would be the same as, or the reverse 
of, what happens in the usual cases. If the power of the mast 
prevailed over the other iron, the effect would be reversed ; but 
• These gentlemen, Messrs Reid, Parsons, Watts, Rennet, "Williams, and Cut- 
field, had been educated in the Royal Naval Architectural College at Portsmouth, 
and were, in every respect, highly competent to, and interested in, the duty assign- 
ed to them by the Admiralty. 
