ij.j6 Water Pipes, lie.— 'Account of Booh. 



At Rome, the inhabitants purchafe the right of conveying water from the public refer- 

 voirs into their houfes. The law prohibits them from making the pipe of conveyance larger 

 than the aperture granted them at the refervoir, as far as the diftance of fifty feet *. The 

 legiflature was therefore aware, that an additional pipe of greater diameter than the orifice 

 would increafe the expenditure ; but it was not perceived that the law might be equally 

 evaded by applying the conical frullum C D beyond the fifty feet. From this fecond rule 

 we learn, that it is not proper to make the flues of chimneys too large in the apartments ; 

 but that it will be fufHcient if they be enlarged at their upper terminations, according to the 

 form CD, fig- ^S- This divergency of the upper part will carry off the fmoke very well, 

 even when it is not practicable to afford chimneys of fufficient length to the upper apart- 

 ments. The fame obfervation is applicable to chemical furnaces for flrong fire. 



3. The pipe B C ought to be ftraight, without elbows or curvatures. To the experiments 

 which Boffut has made on this headf I (hall add the following. 



[To be continued.] 



ACCOUNTS OF BOOKS. 

 Philofophical Tranfaftions of the Royal Society of London, for the Year 1798. Part II. 

 Quarto. 593 pages, with a Lift of Prefents and Index, occupying 12 pages more, and 

 17 plates. Sold by Elmfly, London. 



J. H I S Part contains the following papers : 10. A Difquifition of the Stability of Ships, 

 by George Atwood, Efq. — 11. Quelques Remarques d'Optique, principalement relatives 

 a la Reflexibilite des Rayons de la Lumiere. Par P. Prevoft, Profeffeur de Philofophie a 

 Geneve, de TAcadcmie de Berlin, de la Societe des Curieux de la Nature, et de la Societe 

 Royale d'Edimbourg. Communicated by Sir Charles Blagden, Knt. F. R. S. — 12. An 

 Account of the Orifice in the Retina of the Human Eye, difcovered by Profeflbr Soem- 

 mering : to which are added. Proofs of this Appearance being extended to the Eyes of 

 other Animals. By Everard Home, Efq. F. R. S.— 13. A Defcription of a very unufual 

 Formation of the Human Heart. &y Mr. James Wilfon, Surgeon. Communicated by 

 Matthew Baillie, M. D. F. R.S. — 14. Account of a fingular Inftance of Atmofpherical 

 Refradlion. In a Letter from William Latham, Efq. F. R. S. and A. S. to the Rev. 

 Henry Whitfield, D. D. F. R. S. andA.S (See Philof. Journal, IL 417.)— 15. Account 

 of a Tumour found in the Subftance of the Human Placenta. By John Clarke, M. D. 

 Communicated by the Right Hon. Sir Jofeph Banks, Bart. K. B. P. R. S. — 16. On the 

 Roots of Equations. By James Wood, B. D. Fellow of St. John's College, Cambridge. 

 Communicated by the Rev. Nevil Mafkelyne, D. D. F. R. S. and Aftronomer Royal.— 

 17. General Theorems, chiefly Porifms, in the higher Geometry. By Henry Brougham, 

 jun. Efq. Communicated by Sir Charles Blagden, Knt. F. R. S. — 18. Obfervations of 

 the Diurnal Variation of the Magnetic Needle in the Ifland of St. Helena ; with a Conti- 

 nuation of the Obfervations at Fort Marlborough in the Ifland of Sumatra. By John 

 Macdonald, Efq. In a Letter to the Right Hon. Sir Jofeph Banks, Bart. K. B. P. R. S. 

 — ig. On the Corundum Stone, from Afia. By the Right Hon. Charles Greville, F. R. S. 

 —20. An Enquiry concerning the Chemical Properties that have been attributed to Light. 

 By Benjamin Count of Rumford, F. R. S. M. R. I. A. (See Philof. Journal II. 400.)— 



* Fontln. de aquseduft. art. 205. 106 ct iii. f Art. 631 et feq. 



21. Expe- 



