Some rules on gunnery
Date
8 April 1686
Creator
Unknown, Artist
Object type
Archive reference number
Manuscript page number
vol10 p379
Material
Dimensions
height (page): 308mm
width (page): 178mm
width (page): 178mm
Subject
Description
Diagram in William Molyneux's letter to Edmund Halley dated 8 April 1686, discussing Halley's construction to illustrate the latter's rule of determining angles of shooting with a mortar piece. Molyneux notifies Halley that George Tollet had devised a rule for calculating the angles on seeing Halley's diagram. The letter was read to the Royal Society on 21 April 1686.
This figure is copied from LBO/10/296. The original letter is at EL/M1/94. Tollet's discussion of this problem may be found in Cl.P/1/20 and elsewhere in the Royal Society Archives.
This figure is copied from LBO/10/296. The original letter is at EL/M1/94. Tollet's discussion of this problem may be found in Cl.P/1/20 and elsewhere in the Royal Society Archives.
Transcription
You may Remember, when I was last with you in London you obliged me with your Rule for Shooting on Ascents and Descents with the Mortar-peice, The Proposition is, the Greatest Randon of a Peice: The Horizontall Distance of an Object; and the Height or Descent from the Horizontall Line, being given, to find the two Elevations, or Depression of the Peice necessary to Strike the Given objet. Your Construction is this In the Figure Make AD = greatest Rand: DB = A D -+ Double Height Descent strike the semicircle AEB, Erect the Perpendicular ED, make DG = the Horizontall Distance, and GH = ED, and DF = AD the Greatest Rand, then make FK FL each Equall to H D Draw KG LG the Angles KGD, L G D are the Elevations required and if K fall below D, K G D shall be the Depression. This is your Construction and thereon you have a Rule, Divide the Greatest Random by the Horizon Dist. but I need not repeat it to you you have it in your Pocket Book: I must beg the Favour of you to give me your Demonstration of this Rule, and Construction, you Promised it to me, when I was with you, but my Departure was so suddain, I had not Time to Put you i mind thereof.
Transcribed by the Making Visible project
Transcribed by the Making Visible project
Object history
At the meeting of the Royal Society on 21 April 1686, ‘A letter from Mr. William Molyneux to Mr. Halley, dated at Dublin, April 8, 1686, was read’ (Birch 4:475). The full minutes are printed in Birch 4:475-79.
Related fellows
William Molyneux (1656 - 1698, British) , Science writer
Edmond Halley (1656 - 1742, British) , Astronomer
Edmond Halley (1656 - 1742, British) , Astronomer
Associated place