20 Conduit St
April 15th 1841
My dear Sir
Mr Collen, <1> miniature painter by appointment to the Queen, has requested me to forward you the enclosed note. <2>
I have given the Electrolytic Engine to Henley <3> for him to make some experiments with. The generation of the gases having raised the piston through 1/8 th of its stroke the explosion is sufficient to send it the remainder. The platinized silver electrodes do not answer I have therefore ordered them to be replaced by platina ones. The model would have acted much better if it had a double cylinder instead of a single one; the dead point is constantly stopping the machine.
Yours very truly
C. Wheatstone.
Notes:
1. Henry Collen (1800–1879), miniature painter, calotypist & spiritualist, London.
2. Not located. This may well have been the introduction of WHFT to Collen, who was to become his first licensee of the calotype patent. The earliest known letter is from 24 April 1841 - see Doc. No: 04245.
3. William Thomas Henley (1814–1882), instrument maker.