From John Conwill   July 23rd. 1842.

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Let AB1 = 480000 miles and Cq or qD – the side of a right angled triangle opposite to an angle of 5º 20’,2 the inclination of the moon’s orbit to that of the earth, the hypotenuse3 of the right angled triangle be 240000 miles.

I considered the earth’s path to be surrounded by a glass tube of an oval shape its diameter being AB, CD.

diagram

Could the moon leave a trace behind and that the tube specified could be brought into action a very lengthy spiral would be seen traced on its surface, which line would be the moon’s path around the sun.

July 23rd. 1842. | J. Conwill.

RI MS JT 1/11/3526

1

AB: the diameter of the moon’s orbit.

2

an angle of 5º 20’: ‘the degree of inclination of the moon’s axis to her orbit … is 84º 51’ 11”; or it is 5º 8’ 49” out of the perpendicular’ (Library of Useful Knowledge: Natural Philosophy III (London: Baldwin & Craddock, 1834), p. 83).

3

hypotenuse: the side of a right-angled triangle which subtends, or is opposite to, the right angle (OED).

Please cite as “Tyndall0152,” in Ɛpsilon: The John Tyndall Collection accessed on 29 April 2024, https://epsilon.ac.uk/view/tyndall/letters/Tyndall0152