144 



Mr. Gassiot on AppoM's Apparatus 



[May 17, 



elements to quadratures and thus to complete the solution. 1 notice that 

 whilst the time may fairly he said to be eliminated, the space element 

 may be more properly said to undergo the negative process, if it may be 

 so called, of ab-limination ; it is not introduced into and then expelled 

 from, but prevented from ever making its appearance at all in the resolving 

 system of differential equations. It is from the study of one of these allied 

 but more difficult questions that the present memoir has taken its rise as a 

 collateral inquiry and elucidatory digression. 



11. " On Appold's Apparatus for regulating Temperature and keeping 

 the Air in a Building at any desired degree of Moisture.''^ By 

 J. P. Gassiot, Esq., V.P.H.S. Received May 3, 1866. 



Those Fellows of the Koyal Society who were acquainted with the late Mr. 

 John George Appold, have often expressed their admiration at the various 

 scientific arrangements which he from time to time adapted to his dwelling- 

 house in Wilson Street, Finsbury Square. However intense might be the 

 frost of winter or the heat of summer, or the brilliancy of the gas with 

 which his rooms were lighted, when once under his hospitable roof you 

 enjoyed a pure and refreshing atmosphere. Much of this was undoubtedly 

 due to the steam-power he always had at command connected with his 

 business premises immediately adjacent to his dwelling-house, by which he 

 could at any time force a current of fresh air at a given temperature into 

 any of his rooms ; indeed Mr. Appold always contended that houses could 

 not be made thoroughly comfortable as habitations without the aid of 

 steam-power. But among the many of his arrangements to obtain equable 

 temperature in rooms, there were also those that do not require the aid of 

 steam-power, so seldom applicable in private dwellings, and which, being 

 easy of adaptation, might be used in private houses with much advantage as 

 regards the health and comfort of the inmates. I allude to his Automatic 

 Temperature regulator, and to his Automatic Hygrometer ; and these in- 

 struments, as originally constructed by her late husband, and used for 

 many years in their house, but now repaired and placed in perfect working 

 order by Mr. Browning, Mrs. Appold has requested me to offer in her name 

 to the President and Council of the Royal Society. She desires me to 

 express a hope that they will oblige her by retaining them among the other 

 scientific apparatus belonging to the Royal Society, as a mark of respect to 

 the memory of one who always highly esteemed the honour he received 

 when he was elected into that body in June 1853. 



I annex a description and drawing of both instruments (Plate VII). 



Appold* s apparatus for regulating the temperature of huildings 

 automatically. 



This instrument consists of a glass tube having bulbs at each end. The 



