Alden Partridge’s Notes on Projectile Velocities
Containing the results of some experiments made at the Military Academy at West Point, for the purpose of ascertaining the velocities of cannon balls fired with different charges of powder. February 1815.
|Calibre of the Gun||Height above the ground in feet||Charge in powder||No of shots fired||Greatest distance before the ball struck in feet—||Least distance in ft.||Mean distance in ft.||Difference of mean distances in feet||Time of flight in seconds1|
In the foregoing experiments it is to be observed that the Gun was each time levelled by means of a spirit-level which had been previously corrected and determined to be accurate—The powder for the different charges was not weighed, but measured as accurately as possible, in copper measures which had the weight they would contain marked on them—
The balls used were not good, being old with too4 much windage, and apparently not well made in the first place—better ones however could not be obtained—
Under these circumstances I do not consider that these results are to be relied on as entirely accurate—I am however strongly induced to believe that under different circumstances (when materials proper for making experiments can be obtained) the method here followed, will be found, not only more general, but also more accurate, for determining the velocities of cannon balls, than any hitherto practiced. The principles upon which it is founded I have explained in another place. Should circumstances permit I shall endeavour at some future time, to make a complete course of experiments upon those principles, for the purpose of determining not only the velocities of cannon balls during different parts of a second, but also to ascertain the different resistance of the air to them when fired with degrees of velocity—
|Captain of Engineers|
MS (DLC: TJ Papers, 194:34599–600); subjoined to preceding enclosure; in an unidentified hand; partially dated; with Table and Note on separate pages. FC (VtNN: Partridge Papers); in a bound volume of Partridge manuscripts; partially dated.
1. FC adds an additional blank column for “Remarks.”
2. Thus in MS, but this and figure to left should have the same value. Both numbers may mistakenly repeat those in the row above. FC leaves these cells blank.
3. Word not in FC.
4. MS: “to.” FC: “too.”
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