926 



Observations made at the Apartments of the Koyal Society, with an 

 Appendix." By James Glaisher, Esq., F.R.S. 



Tlie principal object of this paper is the connexion of the results 

 deduced in a former paper from the observations at the Royal So- 

 ciety's Apartments, with the observations at the Royal Observatory 

 at Greenwich, in order to determine mean numerical values, and to 

 establish the laws of periodic variation from this long series of obser- 

 vations ; the two series of observations are here reduced to one and 

 the same series. 



The observations at the Royal Society having been discontinued 

 between the years 1781 and 1786, it was necessary to supply this 

 link in the series, more particularly as these years were distinguished 

 by very severe w^eather, and their omission would have a sensible 

 effect on the results. The deficient observations have been supplied 

 by a comparison of the observations which were made at Somerset 

 House, with the observations during the corresponding years made 

 by Mr. Barker at Lyndon in Rutlandshire, from 1771 to 1799, cor- 

 rections being thus obtained for reducing the Lyndon observations 

 to those at Somerset House. 



By a comparison of the temperature of the air at Somerset House 

 and at the Royal Observatory for every month during the years 

 1833 to 1843, corrections necessary to be applied for reducing the 

 mean values at the one place to those at the other, are deduced. 



Thus the results of the observations at Somerset House are re- 

 duced to those at the Royal Observatory, and a table is given showing 

 the mean temperature at the latter place of each month in every year 

 from 1771 to 1849 inclusive. By taking the means of the several 

 columns in this table, the mean temperature of each month is deduced 

 from all the observations. From these mean monthly temperatures 

 a table is constructed showing the excess of the mean monthly tem- 

 perature at Greenwich for each year, above the temperature of the 

 month deduced from all the years. 



Tables are next given showing the mean temperature in quarterly 

 periods for the year, and for successive groups of years at the Royal 

 Observatory at Greenwich, from the year 1771 to 184'9; and the 

 excess of the quarterly and yearly mean temperatures in every year, 

 and for groups of years, above the means from all the years. The 

 author remarks that the numbers in these tables do not at all confirm 

 the idea that a hot summer is either preceded or followed by a cold 

 winter, or vice versa ; but on the contrary it would appear that any 

 hot or cold period has been mostly accompanied by weather of the 

 same character, and instances are cited in support of this conclusion. 



Tables are also given, based upon the readings of the self-registering 

 thermometers, exhibiting the extreme readings at Somerset House 

 and at the Royal Observatory. 



Incidentally the author goes into an inquiry respecting the relative 

 temperature of London and the country in its neighbourhood. From 

 the observations made by Mr. Squire at Epping from 1821 to 1848, 

 and also from those at Lyndon, he concludes that the general fact 

 of a higher winter temperature and lower summer temperature at 



