COMMITTEES ON BEHALF OF THE GOVERNMENT PWG 
was all of rope, of others part iron and part rope, and still others, 
all iron. The decks of wooden vessels were also often of iron. 
Vessels at this time appear to have carried several compasses 
which were sometimes arranged in pairs, and were placed in 
what were thought to be the most convenient locations. The 
presence of large masses of iron, often within a few feet of 
the compasses caused a large and variable amount of deviation 
on which account navigation was at times extremely precarious. 
Various plans had been proposed from time to time for overcom- 
ing the local attraction, some of which seem strange indeed, such 
as setting the compasses in iron pots four inches thick, placing 
them in zinc cases packed with charcoal, etc. —The method which 
seems to have been most effective was the one invented by the 
English astronomer Airy, which consists in counteracting the 
local attraction by means of bar magnets placed in suitable loca- 
tions. The committee of the Academy adopted this method for 
the war vessels which they inspected, making use of the services 
of an expert, A. D. Frye, of New York, to carry it into practical 
effect. They supervised the correction of the compasses on 27 
vessels of all kinds, including sloops, monitors, gunboats, pro- 
pellers, side-wheel steamers, tugs and transports, and were 
occupied in the task from March until late in September. Some 
of the vessels were at New York, others at Boston, Philadelphia, 
and Hampton Roads. At Philadelphia a compass station had 
not been established, and at the request of the Bureau of Naviga- 
tion, one member of the committee, Fairman Rogers, gave 
personal attention to the ship Ticonderoga, which was lying 
there, and made a special report to the committee. 
In addition, Charles A. Schott and G. W. Dean, assistants in 
the U. S. Coast Survey, made, by direction of Professor Bache, 
an extended series of magnetic observations on the first-rate iron- 
clad Roanoke and the monitor Passaic at the Brooklyn Navy 
Yard, and also some experiments in the iron-clad Monadnock 
at the Charlestown Navy Yard. 
