( 33 1 ) 



Addition, by the Translator. 



On the fame SuhjeB ; from Styieaton's Narrative of the Conjlru&ion 

 of the Edyjlone Light-Houfe. 



IN this work, Mr. Smeaton has given an account of his examination 

 of all the fpecies of Lime or Cement that came to his knowledge ; and 

 he ranks among the firfl;, or mod powerful, the Terras defcribed by Leeu- 

 wenhoek ; and alfo Puzzolana, which is a Cement of the fame kind, brought 

 from Italy, as the former is from Germany. Both of thefe are fuppofed to 

 be volcanic productions ; and if fo, they are fubflances prepared by Nature, 

 in the fame manner as Lime is by art, namely, the operation of fire. Mr. 

 Smeaton recommends, for water buildings, the mixture of Terras or Puzzo- 

 lana, with Aberthaw Lime, and he approves of repeated beating of the 

 Mortar fo made, as it thereby acquires the greater ftrength. 



Mr. Smeaton's fentiments on the preparation of thefe Cements, entirely 

 agree with thofe of Mr. Leeuwenhoek, though our Englifh Engineer feems 

 to have been ignorant of the caufe of the cohefion of Mortar, and of the 

 reafon why it is improved by beating ; which have been fo accurately invef- 

 tigated and minutely defcribed by the Dutch Naturalift. 





