niet ian ail 
Memoir of Rev. John Prince, LL. Dp 207 
of them, dated March 3, 1798, Mr. Jones says, “ It is to you that 
the Air Pump and Lucernal owe their present state of perfection 
and improvement.” In ancther, dated September 29, 1798, he 
says, ‘In all respects I think you have made the Lucernal as com- 
plete and as simple as it can be made.’’ Under the date of March 
4, 1798, Mr. Jones acknowledges the adoption ‘of Dr. Prince’s “ very 
useful and ingenious emendations” in the construction of the * astro- 
nomical lantern machinery.” 
hus a constant intercommunication of friendly offices was kept 
up for nearly forty years. ‘The correspondence is creditable to the 
Messrs. Jones in every point of view. On the part of Dr. Prince, 
it contains a body of instruction such as can no where else be found, 
and would be regarded as an invaluable directory, by all whose bu- 
siness or whose pleasure it is to make use of the instruments of sci- 
ence. 
When we consider the situation of Dr. Prince, conducting his 
investigations and experiments in solitude, far removed from the 
great centers of scientific research and observation, and having to 
communicate with other philosophers by the tedious and unsatisfac- 
tory means of epistolary correspondence beyond the ocean, it be- 
comes truly astonishing to reflect upon the success and amount of 
his labors. Until long after his great invention of the improved 
air-pump, he had depended almost wholly upon his own toil and 
ingenuity in the construction of scientific instruments, not having, 
at that time, established a correspondence with the on ma- 
chinists. He had, of course, to struggle against many inconven- 
iences, from which a vicinity to the London workshops would have 
exempted him. There isa great amount of floating knowledge 
accumulated and mutually communicated where many persons are 
kept for a long time employed in any branch of business, and which, 
never being recorded in books, the self-taught and solitary operative 
will not be likely to acquire. 
The following passage, extracted from a letter written by Dr. 
Prince to President Fitch, of Williams College, Sept. 24, 1795, 
will illustrate the trials and difficulties to which he was subjected in 
the construction of philosophical instruments—it refers to an equa- 
torial. 
“On my return home, the ingenious young map, whom I have 
always employed to do my brisk work, and who had begun the 
brass box for the needle, could not finish it immediately. His 
