Scknti/ic News, -^Account of Boo^t. 329 



ufe ; fuch as wood, turf, and pitcoal, whatever may be their peculiar charaftcrs in other 

 rcfpe£ls. The required equation muft be determined for at lead four different cafes : 



Cafe I. Where the wood, turf, or coal is burned in a furnace to heat a certain volume of 

 air, as for example^ that of a chamber. 



Cafe 2. Where the heat is employed in producing the flate of ebullition, in a fluid pro- 

 per to boil certain fubflances plunged in it. 



Cnfe 3,, Where the heat is employed to harden foft matters, fuch as clay for tiles. 



Cafe 4. And where certain hard or confidant matters, fuch as metals, are required to 

 be liquified by heat in a furnace or'forge. Each of thefe equations grounded on various 

 experiments muft be found and eftabliftied analytically, fo that it may be poffible to deter- 

 mine with precifion the ratio of the calorific efFeft, and.confequently the degree of utility^ 

 in economical applications of every kind of wood, turf, or pitcoal. . 



III. Natural Philcfophy. — To find by experiment the greateft degree of heat which water 

 in the ftate of vapour can communicate to other bodies ; and to anfwer the queftion, whether 

 that part of the water in Papin's digefter, which is not converted into fteam, can acquire 

 a more elevated temperature than 21 2" of Fahrenheit. 



IV. Philofophy. — What are the moft remarkable degrees, through which pra6llcal philcfo- 

 phy has palled from the time in which it was firft treated fyftematically to the prefent time. 



The memoirs in anfwer to thefe queftions are required to be written in Latin, Danifh, 

 or German, and fent. before the end of June 1799) to the Secretary of the Society, 



Profeflbr Abilgaard. 



Berlin, " 

 The Phyfical Society at Berlin has announced the following Queftion, for a Prize of 20 



Holland Ducats. (9I. 5s.) 

 ADMITTI NG that Eledricity is a neceflary Agent for the formation of Hail, are there 

 any grounds for concluding, that the Eleftrical Cloud can be rendered incapable of gene- 

 rating Hail, as Lightning is prevented by Conduftors ? What are the means to be adopted 

 for this purpofe, and the fa£ts or obfervations in general upon the fubjedl which deferve 

 notice ? 



Proceedings of the Aflbciation for promoting the Difcovery in the interior Parts of 



Africa, &c. 

 Abftraft of Mr. Park's Travels. [Continued from page 283.] 



INFORMATION of a confiderable river flowing through the centre of Africa, be- 

 tween the latitude of 15° and 2C° north, had been received at very early periods from differ- 

 ent quarters, which at difl^erent times was fuppofed to be part of the Senegal and of the 

 Gambia. Further enquiries, however, though they confirm the ancient accounts, (hewed 

 that this river was not only of greater magnitude than either the Senegal or Gambia, but 

 flowed in a contrary direction, running not to the weftward into the Atlantic, but from 

 weft to eaft, to regions unknown. The Moors defcribed it by the name of Nil il Abeed, or 

 tlie River of Slaves : the Negroes beftowed upon it the appellation of Joliba, or the Great 

 Waters. Something, however, of doubt ftill remained, particularly with regard to its 



eaftera 



