William Whewell to Faraday   7 February 1852¹

Trin. Lodge, Cambridge | Feb. 7, 1852

My dear Sir

I am much obliged to you for the specimens of magnetic curves² which I received two days ago. I have been thinking what word will best answer your purpose, but it is difficult to decide such a question without knowing the kind of connection in which it is to be used. Spheroid would describe the surface which you wish to express but is not mechanical enough. You might perhaps get on in English by calling it the spindle shaped surface or fusiform surface, but a new word would be better. I should recommend you to call it the sphondyloid surface, and then, the sphondyloid simply, making it a substantive. Sphondylos in Greek is a pulley or socket which turns on an axis, a spindle, a vertebra, and the like, and is already familiar in anatomy and botany. Used as a substantive sphondyloid will group well enough with solenoid which has been adopted by English writers.

It is rash to suggest anything to you in the way of manipulation; but would not some magnetic curves come out more neatly if instead of filings you were to use fine wire cut into minute lengths.

I am glad you are going on with your magnetic speculations and am always

Yours Truly | W. Whewell

Dr Faraday

Endorsed by Faraday: Sphondyloid ³.