xii CONTENTS. 



96 feet. The water was drawn off, and the fand dug out, till only 36 feet remained ; when fand 

 and water again rufiied in to the former height. The current of water was then continued by- 

 pumping, and part of the fand raifed through the water by heavy valve buckets. During this laft 

 procefs the water gradually role and increafed in quantity fo as to overflQW the top at the rate of 

 46 gallons per minute. 



Scientific NewSj and Accounts of Books • — • — p. 279 



Compofition for extinguiftiing fire. — Travels in Africa by Mr. Mungo Park. — Proceedings of the Afri- 

 can Aflbciation — Account of Mr. Park's route and dlfcoveries. — Table for reducing Englifti 

 meafures and weights into French. — ^Table of the prices of neceflaries, day-labour, &c. fince the 

 Conqueft. By Sir George Shuckburgh Evelyn, Bart. F. R. S. and A.S. 



OCTOBER 1798. 



Engravings of the following ObjeSls: i. The Art of Speedy and Swift Intel- 

 ligence. 2. Sir R. L. Edgeworth's Portable Telegraph. 



I. Curious Circumftances upon which the Vitreous or the Stony Characters 

 of Whinftone and Lava refpeflively depend ; with other Fafts. In an Ac- 

 count of Experiments made by Sir James Hall, Bart. F.R. and A.S. S. 

 Edin. — — — — — — p. 285 



Objeftion to the igneous formation of whihftone or bafaltes, which by fufion affords glafs. Di(^ 

 covery that the vitreous character is owing to fpeedy refrigeration, and that the ftony charaifterwith 

 a lefs degree of fufibility is afforded by flow cooling. Valuable induftions, with a. table of the ra- 

 fuHs of experiment. 



II. On the Analyfis of Pumice, which is found to contain Potafli ; and of 

 Bafaltes and Lava, containing Soda. By Dr. Kennedy — p. 289^ 



III. Experiments and Obfervatlons on the Preparation, and fome remarkable 

 Properties, of the Oxygenated Muriate of Potafli. By Mr. Thomas Hoyle, 

 jun. — — — — — p. 290 



Preparation of the oxygenated'muriate of potafli, and its foltition in water and' acids. Effeflis of light 

 and heat. Detonation with, a great number- of combutlible fubftances with the fait by friAioH and 

 the acids. 



IV. Obfervations on the Natural Hiftory of Guiana. In a Letter from Wil^ 

 liam Lochead, Efq. F.R.S. Edin. to the Rev. Dr. Walker F.R.S. Edin. 

 Regius Profeflbr or Natural Hiftory in the Univerfity of Edinburgh, p. 29,7 



Goad of Gruinea. Striking appearance of the fky — within the tropics. Winds, dews, fogs, and tem«, 

 pemturc. Face of the country. Defcription of the Savannahs. 



V.Oh 



