THE COMMERCIAL GYROSCOPIC COMPASS. 
By Eimer A. Sperry, Eso., MEMBER. 
[Read at the twenty-fourth general meeting of the Society of Naval Architects and Marine Engineers, held in 
New York, November 16 and 17, 1916.] 
The writer much appreciates the honor accorded him of making through the 
medium of the Annals of this Society the first public announcement of a new navi- 
gational instrument of precision, adapted to the merchant marine and also to the 
secondary fleets of our navies. 
With the advent of the gyro-compass for navigational purposes, there was 
introduced for the first time an instrument of precision whereby courses could be 
laid with great accuracy, and dead reckoning computed with an exactitude there- 
tofore impossible. The following illustrates the practical effect of this accuracy 
upon the navigation of our own navy. After the third compass had been installed 
on our battleships some years ago, the Bureau of Navigation called the writer’s 
attention to a significant fact, namely, that it had been universally reported that 
“currents” had disappeared. To the writer, whose life work had been more or 
less intimately connected with electric currents, none other occurred to him, and 
he was accordingly mystified. However, this announcement really had far-reach- 
ing significance, inasmuch as it seems that “currents” are the scapegoat upon which 
the delinquencies of the magnetic compass and the faulty calculations due thereto 
had for years been fastened. This statement, therefore, was tantamount to the 
announcement that at last a compass had been found which could be relied upon 
as being true to the geographical meridian. 
There have been constructed here in New York and installed by our engineers 
in various navies of the world about 600 gyroscopic navigational equipments, 
with their repeaters and other instruments and adjuncts. The major portion has 
been installed in the American, English, French, Italian and Russian navies. So 
far as known, the British Admiralty have the largest number of equipments in 
service at the present time, although other nations, including Japan, are installing 
the compasses rapidly. Considering the size of the navy, the largest number of 
compasses, strange to say, is employed probably by Denmark, although Spain may 
be considered a close second. 
Perplexing and fitful are the disturbances to which the magnetic compass 
falls heir in increasing ratio as ships represent larger and larger masses of steel, 
and as cargoes contain steel and iron to an increasingly greater extent. It has been 
known for years that when a cargo consisting of a large steel component, such as 
ordnance, shifts even very slightly, all the magnetic compasses are at once dis- 
turbed. Steel cargoes, or parts that at some time in their history have been han- 
