215 ON STONY AND METALLrNE SUBSTANCES 



XVII. 



Method of applying a temporary Forcer to a Pump, fo as to pro- 

 duce a conftant Stream. By Mr. Richard Trevithick *'. 

 From the Author. 



Additional forcer JL HIS contrivance which, on feveral occafions, may prove 

 pump OI producing u ^ eU1 ^ confifts in fixing a barrel with a folid pifton alongfide 

 a conftant of the common pump, in fuch a manner, that the lower fpace 



ftream. Q f ^ e additional barrel may communicate with the fpace be- 



tween the two valves of the pump, and laftly, by connecting 

 Defcription. the rot j s f that they may work together. This is (hewn in 

 f\g. 4, plate XI. and the effect is, that when the piftons are 

 raifed, the fpaces beneath, A and B, become filled by the 

 preffure of the atmofphere, at the fame time that the upper 

 column flows out atE. But again, when the piftons defcend, 

 the valve C fhuts, and, confequently, the water driven by the 

 pifton in B muft afcend through A, and continue to produce 

 an equal difcharge through E in the down ftroke. 



XVIII. 



Experiments and Obfervations on certain fiony and metalline 

 Subftances, which at different Times are /aid to have fallen 

 on the Earth ; alfo on various Kinds of native Iron. By 

 Edward Howard, Efa. F. R. S. From the Philofophical 

 Tranfaclions, 1802. 



Stony and J[ jjg concordance of a variety of facts feems to render it 



ftances havcun- rnoft indifputable, that certain ftony and metalline fubftances 

 doubtedly fallen have, at different periods fallen on the earth. Whence 



their origin, or whence they came, is yet, in my judgment, 



involved in complete obfcurity. 



The accounts of thefe peculiar Subftances, in the early 



annals, even of the Royal Society, have unfortunately been 



blended with relations which we now confider as fabulous ; 



and the more ancient hiftories of flones fallen from heaven, 



* This Gentleman's name was, by miflake, printed Trevithack, 

 in Vol. I. 161. 



from 



