Account of the Pearl Fijhtry in the Gulph of Mhnair. S t 



(haft or drain, it would be pradlicablc by the fall of part to raife the remainder to the top of 

 an houfe or building for domeftic or other purpofes. In this cafe it would be requifite to 

 place the firfl: vefTel D at the bottom of the fliaft, and the fecond I at the level of the ftream, 

 and the operation of this inverted engine would force water nearly as high above that level 

 as the depth of the fhaft might be below it. 



If the afcending and defcending columns were of equal length, they would be in equilibrio, 

 and no more water would rife than juft to fill the lower tube. The velocity of afcent, fup- 

 pofing fufhcient water way, and other circumftances, fuch as the inflexions of the pipes, to 

 be properly difpofed, will depend on the excefs of length in the defcending column, and 

 this excefs is capable of a maximum relative to the quantity raifed to a given height, or as 

 engineers call it, the efFeft. The longer the lift, the lefs the quantity raifed, fuppofing the 

 upper refervoir to be of a given magnitude, the denfities of air being inverfely as the 

 prefl'ures, or length of the prefllng column, and the quantity raifed being equal to that of 

 the air in its comprelTed ftate. Whence it follows, that the whole quantity raifed will be 

 lefs the fewer the lifts. 



I do not underftand the hypothefis upon which this machine was conftru6led. The re- 

 fcrvoirs have their capacity as 2 to i . But the air fubjecled to the re-a£lion of a column of 

 *i6 toifes, befides the common preffure, would fuftain the preflure of four atmofpheres, and 

 therefore be condenfed into one-fourth the fpace. If there be no fallacy in this plain 

 remarkjit mufl follow, that the lower veflel I was only half emptied when the ftream ccafed 

 to be afforded at O, and, confequently, the efFe£l was only half what is here ftated. 



That air condenfed to one-fourth fhould take up and diflblve more water than in its 

 ordinary rare flate, and afterwards depofit it when it recovered its original dimenfions, 

 is confentaneous with other well known fa<£ls; and the modern theorifts will eafily 

 apply the doftrine of latent heat, or the increafed capacity of expanded air, to account for 

 the phenomenon of its robbing the water not only of the heat which maintained its ftate of 

 elaftic folution, but even that which would have been requifite to keep up the ftate of 

 common denfe fluidity. W. N. 



v.. 



An Account oj the Pearl Fifliery in the Gulph oJManar, in March and April iygy. By 



Hmnry J. Le Beck, Efq. 



{Concluded from Vol. III. page 54.7.), 



X HE diving ftone is a piece of coarfe granite, a foot long, fix inches thick, and of a 

 pyramidical fliape, rounded at the top and bottom. A large hair rope is put through a 

 liole in the top. Some of the divers ufe another kind of ftone fliaped like a half moon, to 



bind. 



