Coast Survey of the United States. 245 
out. of gear when the division of the whole circle is completed. 
The centering was found defective, but now this and all other 
errors are effectually removed, except some small irregularities in 
the teeth of the main wheel, which will, in turn, be corrected. 
This engine admits a circle four feet in diameter, and will an- 
swer for the whole country. 
There is one respect in which the superintendent has adopteda 
course entirely new, which must meet with the hearty approba- 
tion of the friends of learning throughout the country. In vari- 
ous parts of the United States, but principally attached to learned 
institutions, are found gentlemen who are led by taste, as well as 
professional pursuits, to make observations of value to the coast 
survey, especially in latitudes and longitudes. The superintend- 
ent purchases their results, of the highest value, because made 
by experienced observers, and with better instruments than the 
coast survey could furnish. Professors may profitably employ 
their summer vacations in similar labors. It will be recollected 
that Dr. Bache himself, while filling a chair in the University of 
Pennsylvania, made the magnetic survey of his native state 
during the term intervals of two years. Prof. Renwick, of Co- 
lumbia College, was engaged last year in making experiments in 
Long Island Sound, with the new magnetic instruments before 
spoken of, for the coast survey. Mr. Bond, of Cambridge, com- 
municates the meridian differences, by chronometers, between 
Boston and the British observatories. ‘These have become nu- 
merous since the establishment of the line of steamers, and the 
commencement of Commodore Owen’s survey of the Bay of 
Fundy. And Mr. Walker, of Philadelphia, has in charge the 
reduction of all the observations on record at the office, bearing 
upon the longitudes of coast-survey positions. Every one will 
admit that this duty, as extensive as it is laborious, could not be 
placed in more responsible keeping. 
In the same spirit, observations at fixed observatories, occulta- 
tions, eclipses, and moon culminations, and also for latitude, are 
procured and reduced to central points of the survey. It has al- 
ready been mentioned, that the results of the transits over the 
prime vertical at Cambridge, have been communicated by Prof. 
Peirce. This system is the more necessary, because the coast 
survey can neither supply instruments nor observers for important 
occasions. ‘The solar eclipse and transit of Mercury of last May, 
Vol. xt1x, No. 2.—July-Sept. 1845. 32 
