31st March 1855
My dear Frankland.
If you should be writing to LeNoir1 would you be kind enough to order a Pachytrop2 for me. I think you said it was £2-10 – I lecture on Voltaic Electricity after Easter3 & if I could have the Instrument within the coming month I might make use of it my course.
Most sincerely yours | John Tyndall
JRL Frankland, 192
LeNoir: George André Lenoir (1825–1909), chemist and instrument maker in Vienna who in 1847 had studied with Bunsen in Marburg, where he met Frankland and Tyndall. See also letter 1053.
Pachytrop: A pachytrop(e) is an electromagnetic device through which an induced current is produced by spiral coils. By using different settings of the pachytrop – involving different resistances of the circuits – the output can be altered; for example, a small quality of electricity (current) at a high intensity (voltage), or a large current at low intensity.
I lecture on Voltaic Electricity after Easter: Tyndall delivered a course of lectures at the RI on ‘Voltaic Electricity’ starting on 17 April and ending on 5 June 1855.
Please cite as “Tyndall1062,” in Ɛpsilon: The John Tyndall Collection accessed on