' of Processes in the Fine and Useful Arts. 351 



remark is not justly applicable to gold, whose dilatation is 

 greater than that of steel. It is easy to conceive the difficul- 

 ties which must be encountered in executing out of the hard- 

 est stones the delicate pieces which enter into the composition 

 of a watch like this. The execution of this watch presupposes , 

 a remarkable progress in the art of working precious stones, 

 and we must give M. Ilebillier credit for great talent, address, 

 and perseverance. 



% Account of Dr Ranken''s Thermantidote for cooling apart- 

 ments in hot climates. 



The thermantidote is a species of ventilator which has been 

 not inaptly compared to a winnowing machine, the revolving 

 of which sucks in air from without. The improvements in 

 the thermantidote consist in its being altogether rendered less 

 complex in its structure, and more easily manageable by na- 

 tive servants, so as at the time to increase the ventilating and 

 cooling power. We cannot without the aid of a figure make 

 the alterations and details of the machine comprehensible to 

 the general reader ; suffice it to say, however, that after the 

 improved mode of construction, the wings of the thermantidote 

 will revolve sixty times in the minute, under the same exer- 

 tion which, on the old plan, would produce only forty revolu- 

 tions in the same time. The alteration suggested may be 

 made by an ordinary carpenter at very little expence. Dr 

 Ranken has also studied to render the machine much more 

 portable than it was before ; which will render it particularly 

 convenient for cooling tents, which many have to live in dur- 

 ing the hot winds. His belief also remains unchanged, that a 

 barrack, or any large apartment, can be more effectually and 

 cheaply cooled by ventilators on the improved thermantidote 

 principle, than by tatties. It should at the same time be borne 

 in mind, that thermantidotes may not be found applicable to 

 every place built originally without the contemplation of their 

 use, unless certain alterations be made. They appear to act 



chronometers of rock crystal, to avoid contraction and dilatation, and the 

 magnetic effects produced by metallic balances. Pendulum rods, with pen- 

 dulum springs of mica, have for several years been under trial in Edin- 

 burgh, and succeed beyond expectation. — Ed. 



