344 0/7 the Use of Zinc for covering B/zilJings. 



discovery of these satellites is entirely owing to the liberal 

 support wherebv our most benevolent Kins; has enabled his 

 humble astronomer to complete the arduous undertaking of 

 constructing this instrument." 



To conclude : — On a review of all Dr. Herschel's observa- 

 tions already made with this telescope, it appears, beyond 

 contradiction, that he has fully succeeded in givinai; it the 

 properties and superiority originally aimed at in its con- 

 struction, how n)uch soever Lalande has been led to dis- 

 parage it. 



Indeed, his two discoveries of Saturn's sixth and seventh 

 satellites would of themselves be sufficient to render this te- 

 lescope ever memorabh-, and surelv ought to have prevented 

 it from having been so much misrepresented. 



Arctueus. 



LIV. On the Use of Zinc for covering Bnildlnrrs. By 

 James Randall, Esq. Architect. 



To the Editor of the Philosophical Magazine. 



T ^^'^' 



X SHALL feel myself obliged bv your inserting the following 



account of an attempt which I have made to introduce zinc 



as a covering for buildings, and of the defrree of success that, 



lias attendeded the undertaking. I am, sir, 



^, , Your obedient servant, 



.Upper Charuon street, 



fitzroy-square. .J AMES KANDALL. 



Zitic is one of the metals that has been hitherto thought 

 unfit for any of the purposes to which the malleable metals 

 are commonly applied. It is said to possess too uuich brit- 

 tlcncss and want of ductility. Messrs. Hobson and Syl- 

 vester, of Sheffield, assert, " that at a temperature between 

 210° and 300° of Fahrenheit it is really a malleable inetal, 

 that it yields to the hammer, and may be wire-drawn if kept 

 at this temperature during the operation; they say likewise, 

 that after having been thus annealed and wrought, it con- 

 tinues soft, flexible^ and extensible, and does not return to 



its 



