Compares actinometric measurements of radiation. Explains interest in total eclipse relative to actinometry. Discusses the possibility of making actinometric measurements by photographic means.
Compares actinometric measurements of radiation. Explains interest in total eclipse relative to actinometry. Discusses the possibility of making actinometric measurements by photographic means.
Proposes meeting times in town. Suggests that JF observe the upcoming total eclipse astronomically. Agrees with JF's seemingly 'cold &c' circular on scientific partnerships, while regretting that it needed to be written.
On RM's stepping down as president of Geological Society. Where exactly abroad will RM pursue enquiries?
Instructions for preparing liquid for the actinometer. Describes 'very strange' experiments on the spectrum as well as an 'unusual' cloud formation.
Clarifies role and methods of R.S.L. Council and scientific committees, suggesting that members of Physical Committee need to be better informed about its activities.
Discusses how exceptional observations of meteorological and magnetical phenomena should be recorded and what significance should be attached to them. Cannot attend next meeting of committee.
Sets up approximate meeting time, depending on his family's timely departure to Antwerp, with JF at the R.S.L. apartments.
Discusses JH's spectrometer and possibility of using surplus from R.S.L. Donation Fund for its construction and enquiry with it into nature of light and heat.
Is confident that by summer his sweeps will all be reduced and arranged in three catalogs for JH's Cape Results.
Met Friedrich Bessel at the Manchester B.A.A.S. meeting; invited him to Collingwood, where he expects Bessel in a few days. Enclosed with the letter a specimen of a new photographic process called 'Chrysotype.' Marvels at traveling from Hawkhurst to Manchester round trip (420 miles) in under 23 hours!
Reports the erection of an obelisk at Feldhausen to commemorate the site of JH's 20-ft. reflector. Back at Cape Town, Thomas Maclear is measuring N. L. Lacaille's Arc of the Meridian. JH received the Prussian Order of Merit.
JH finished his catalog of stars for his Cape Results; hopes to be finished with his nebulae and double star catalogs soon.
Thanks for RH's paper on mineralogy. JH has explored use of mercury together with iron in photography.
Some information about Charles Piazzi Smyth. JH needs information about some of RH's photographic paper, which JH has tried but without success.
Believes that the operative rays in JH's thermographic process are neither 'calorific' nor 'thermal'.
Sends GA a spectrum photograph, and explains how JH obtained it.
Sends GA two more spectrum photographs [see JH's 1842-4-10], and believes that these may lead the way to color photography.
Finished the reductions of all of the nebulae and double stars recorded at Cape Town; JH soon hopes to prepare for the publication of his Cape Results.
Sends RH a packet of photographs with a description of each type.
Remarks that he is 50 years old, and that he and CH have 'seen something of that odd and most changeable compound called Human Nature.'