Is starting for Weisbaden to take the waters in hope of curing his rheumatism. Unable to send the rose he promised Lady Herschel. Sends some sheets of his own lectures.

Has found a method of making a gum equal to gum arabic. Would like the support of the Royal Society and JH to enable him to take out a patent.

Received yesterday a letter from G. B. Airy informing him that JH also observed the meteor of 24 April; sends an account of it. Would also like JH's account to compare the two. Is obliged to JH for trying to get his printed paper filled.

Will find the reference to S. D. Poisson in his own paper on the Heat of Vapours. The subject is in a state of confusion. John Southern's experiments are detailed in John Robison's Mechanical Philosophy, which can be sent from the R.S.L. library if JH does not possess it already.

Much obliged for JH calling but regrets he was out. The question [on steam] they have been discussing seems to be answered by a paper by a Prof. Karl Holtzmann he has just come across; comments on this. If JH is coming to S. J. A. Compton's (2nd Marquis of Northampton) soiree will he come and dine at St. James' Place?

Was not aware when he wrote his paper that doubt existed regarding the invariability of [the absolute heat of steam?]. Comments on the variations in the theories of S. D. Poisson and Karl Holtzmann. The experiments JH suggests would be highly interesting. Would he like to see Holtzmann's paper?

Has no doubt that any improvements JH suggests should be published. [John?] Taylor has borrowed Holtzmann's pamphlet, which will be sent as soon as returned. Karl Holtzmann's formula for air appears quite out. Gabriel Lamé evades the question. If JH writes anything on his calorimeter hopes he will mention the various questions raised.

Further regarding the various theories on the latent heat of steam. Agrees with JH regarding the magnetic observations. Hudson's Bay Company has sent a large bill for J. H. Lefroy's expenses, which the R.S.L. declines to pay. Fears that Edward Sabine is out of humor about something.

Now sees JH's point regarding the theory of steam. Comments on various experiments. Glad to see JH approves of repeating John Southern's experiments. Unable to go to Cambridge; his banking business requires unceasing attention. Doing all he can about the observations. Council will take up the East India observations.

Is JH aware that the magnetic and meteorological observations now being made at Greenwich are to cease at the end of the year? As JH was zealous for these observations he may care to write to S. J. A. Compton (2nd Marquis of Northampton). It escaped his notice that S. D. Poisson and J. B. Biot referred to saturated steam. Return John Robison and Karl Holtzmann to Mansion House when he has read them. Has consulted Thomas Graham about repeating John Southern's experiments.

Agrees with JH that the Government Observatories at the Cape and St. Helena require mature consideration. Greenwich observations are a different matter and were suggested by the R.S.L. Committee of Physics. Has directed the minute to be sent to JH. Has been studying the wet bulb question.

The magnetic and meteorological observatories were never part of any other system. Is not certain whether the Visitors had anything to do with these observatories. Captain Herbert in an Indian journal has proposed a formula for the wet bulb thermometer. Has arranged for the notice to be sent to JH.

The President was requested to write to the East India Company about the observatories. Continuance of the magnetic observations at Greenwich was referred to the Committee of Physics. Cannot find where Nicolas Clement-Desormes's observations are published. Has been studying the wet bulb problem. Capt. Herbert has denounced the article on hygrometry in Brewster's Encyclopaedia.

Has been with Philip Melvill of the East India Co. discussing the printing of the observations. Would it be a good use of JH's photographic papers to take a reverse of William Parsons' (3rd Earl of Rosse) drawings of nebulae? Cannot obtain Nicolas Clement-Desormes's or John Sharpe's papers. Doubts if the mode of measuring latent heat hitherto used can be recommended for accuracy.

About a number of astronomical matters, including double stars. Provides observations and calculations for Gamma Virginis. Also comments on lunar models.

Asks JH's opinion on a paper on magnetism by Karl Reichenbach, which has some 'very extraordinary' statements.

Regrets to learn that JH is still suffering. Advises him to come to London for examination.

Was gratified to hear of the improvement in JH's health. Hopes it will progress.

Informs JH that he is to work with a committee of the B.A.A.S. to prepare a map of the distribution of coal around the world.

Expands on the work of the coal map committee [see JP's 1845-7] by sending along the resolution that created it.