Thursday, April 6, 2017

Early Telescopic Sight

I saw this once before, and fortunately found it again:
Mr. Owen Biddle is desired to procure a Rifle that will carry a half pound Ball, with a Telescope sight…. [Pennsylvania State, Colonial Records of Pennsylvania (Harrisburg, Penn.: 1852), 10:332]
Telescopic sight in 1775?  1/2 pound ball is 227 grams.  I'm told this is about a 1 1/4" bullet.  No, it's .66 caliber. V=4/3*pi*r^3 and lead is 11.3 g/cc.  r=0.66, so 1.32 caliber.

5 comments:

Rusty Miller said...

A 1/2 pound lead ball (a 2-bore) is more likely about 1.25" in diameter.

James Gibson said...

Agree, by the math its a 1.33 inch diameter. Clayton, you forgot that the equation for the volume of a sphere uses the radius. So you are correct that the bullet would be 0.66 in radius. Something about this however reminded me of passages in Hicks on Wall Guns. In 1847 two experimental wall guns were made at Springfield and Harper's Ferry. The important point in the Hicks reference is that the bullet was to be conical and weighed 3 ounces (actual gun bore being 0.75). So I would suspect your reference to a half pound ball in 1852, is actually a conical ball and not a true sphere. I find references to the standard Minie ball (0.58 bore) being 500 grains in weight or 1.14 ounces. In short I doubt you can compute the actual bore of this 1852 rifle based on the weight of the bullet. Its going to be large, but not 1.33 inches in diameter.

ErolB1 said...

The radius of a 1/2 lb lead ball is ~0.66 inches. The diameter, of course, would be twice that.

dittybopper said...

Yeah, it's definitely *NOT* .66 caliber. I shoot a .62 caliber and the balls weigh about 360 grains (7000 grains in a pound). That's about a 20 gauge. Even a 12 gauge (up near .75 caliber) would mean there are 12 balls per pound of dead soft lead that would fit. A half-pound ball means 2 bore, and 2 bore is about......

1.67 / cube root(2) = ~1.16 inches in diameter.

Checking to make sure that's right for a 20 gauge:

1.67 / cube root(20) = 0.615, which rounds up to 0.62".

Rick Boatright said...

Full text - image of original document from the Hathi Trust available at https://babel.hathitrust.org/cgi/pt?id=chi.102220746;view=1up;seq=350

OCR Text from Hathi Trust:

September 7th.
-—In Committee of Safety.

PRESENT: . Benjamin Franklin, John Cadwalader, Daniel Roberdeau, ,Henry Wynkoop, Owen Biddle, Anthony Wayne.

Mr. Owen Biddle is desired to procure a Rifle that will carry a half pound Ball, with a Telescope sight, and to get repaired aRiflle produced by Colo. Wayne.

The Board being informed, by enquiry of the Honorable Peyton Randolph, Esqr., that the application of Colo. George Slaughter, for leave to purchase Gunpowder for the use of a New Settlement in Virginia or Kentucky, is founded in necessity for the protection of a number of Families, they not being able to furnish themselves ' elsewhere, have agreed to permit their purchasing one hundred pounds weight at York Town, in this Province, if the Committee of that Place think fit to spare the same. The above minute was signed by the president & Colo. Slaugh- ter, furnished therewith.