Ɛpsilon

To William Francis1

My dear Francis.

I have 3 little commissions which I should feel greatly obliged to you if you would execute for me.

  • To send me the 2nd course of Lardner’s Handbook of Nat. Phil.2 published by Taylor & Walton – containing – Heat. Electricity Magnetism. Astronomy.

2nd. To purchase or borrow for me a prism of crown or plate glass – a right angled isosceles prism – having its hypotenuse about 2 inches in length and its thickness about ¾ of an inch –

  • To send me a piece of crystallised carbonate of iron. Say a quarter of a pound weight or more if you can get it.

as ever yours | J Tyndall

Monday

Sketch of prism

diagram

The thin vertical surfaces hypotenuse surface and two side surfaces must be polished – I dont care whether the bases are polished or not | JT

A single fully-developed crystal of carbonate of iron would be a great prize to me if I could procure it – The large mass for which I send is intended to be pulverized.

RDS 27/36

1

[mid-October—mid-November 1852]: date is uncertain; any time from the publication of Lardner (n. 2) in late September to mid-November is possible. We presume that Tyndall would have asked Francis to obtain a crystal in London prior to asking Hirst to send one from Berlin (in letter 0691 of 28 November). The latest possible Monday (before letter 0691) is 22 November.

2

Lardner’s Handbook of Nat. Phil.: D. Lardner, Handbook of Natural Philosophy and Astronomy, Second Course: Heat, Common Electricity, Magnetism, Voltaic Electricy (London: Taylor, Walton, and Maberly, 1852).

Please cite as “Tyndall0687,” in Ɛpsilon: The John Tyndall Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/tyndall/letters/Tyndall0687