IMPROVED AIR PUMP. 0QJ 



VIII. 



Account and Defcription of an improved Air Pump. Bj/ Mr. 

 N. Mendelssohn. 



To Mr. NICHOLSON. 

 SIR, 



VJ'N entering Into bufinefs, as a mathematical infirument- Introdu&ory 

 maker, I refolved to make it my principal ftudy to introduce ,etter * 

 into them all the improvements which the prefent advanced 

 date of fcience, the nature of the fubjecl, and my humble 

 abilities would allow. Thus I have begun with improving 

 Volta's electrical lamp and the air-pump. I imagine, I have 

 rendered the ccnftru&ion of the latter much more limple than 

 it ufually is, and confequently lefs liable to derangement, at 

 the fame time that it po defies a very great exhaufting power. 

 Give me leave, Sir, to offer you a defcription of this improved 

 air-pump with the requifite drawings. It is ready for your in- 

 fpedlion. I (hall think myfelf very happy, if this ufeful phi- 

 lofophical instrument meet with your approbation. And if it 

 be fo fortunate, I requeft you the favour of introducing it into 

 public notice, by inferting my paper in your excellent and 

 defervedly celebrated Journal. 



I am, with the higheft efteem, Sir, 



Your humble and obedient fervant, 



N. MENDELSSOHN. 

 No. 50, Surry-Street, Black-Friars, 

 Feb. 13, 1805. 



Notwithstanding the many improvements which have been Defcription of 

 made upon the conflru&fon of the air-pump, it was dill de- Mendelflbhn's 

 , , , f i-/- j • improved an- 



lirable that this initrument fhould be more fimplihed in its pump . 



mechanifm, and yet poffefs the fame advantages of thofe con- 

 ltru61ed lately. That the mechanical power of the pump, and 

 not the predure of the air, (hould open the valves, has long 

 been required and already done by Mr. Cuthbertfon, Mr. Haas, 

 and feveral other fkilfijl artids; but may I be allowed to remark, 

 that on reading the defcription of their indruments, they ap- 

 peared to me to be too compounded. It mud be very dilficult 



for 



