364 Mr G. Merry weather's account of' a new Jppaj-atus. 



spirit lamp*; as^soon^as the balls^are red hot, the vapour of the spirit is ex- 

 cited, and renders the dropping of stronger alcohol quite unnecessary. For 

 this suggestion I am indebted to Professor Christison. 



When it is wished to have any lower degree of temperature, the experimen- 

 ter has only to withdraw some of the brass tubes, in doing which he takes 

 away at the same time the wicks and platina balls ; corks must then be placed 

 in the tin tubes, to prevent the unnecessary evaporation of the spirit. 



Thoughts Oil the Casting of Statues in Metal. By John 

 RoBisoN, Esq. Sec. F. R. S. E. 



W HEN we consider, in a superficial manner, the comparatively 

 small number of ancient bronze statues which have reached to 

 our times ; or read the animated, though somewhat ludicrous, 

 account given by Benvenuto Cellini, of the obstacles he en- 

 countered in casting the statues of Perseus*; and when we ad- 

 vert to the large sums required in the present day for casting 

 works of art in bronze, we are at first apt to imagine that 

 the great cost of such works must be the consequence of some 

 mysterious difficulty in the process ; but if we go on to examine 

 more closely into the grounds on which this opinion is founded, 

 we begin to perceive the anomaly of any such difficulty being 

 supposed to exist in this country, where immense works have 

 been executed in cast-metal, works requiring a rigid accuracy of 

 ultimate dimensions not at all necessary in statuary, in which, if 

 the relative proportions be truly kept, no injurious effect is pro- 

 duced by the shrinking of the metal which takes place in cool- 

 ing f. 



On farther consideration, we are compelled to admit, that 

 where skilful founders and capacious furnaces abound in every 

 district, where the most intricate castings are daily and hourly 



• Cellini's difl&culties must have arisen from want of power in his furnace, 

 as he says he overcame them by debasing his bronze with pewter, and by 

 getting some well-dried firewood from a neighbour. 



•f- The casting of a cylinder for a steam-engine of 200 horses power, is a 

 more delicate operation than that of a group of statuary ; an air-hole or flaw, 

 which might be imperceptible, is easily repaired in the statue, would be fa- 

 tal to the other, though it might not be discovered until great expense had 

 been incurred in finishing it. 



