352 Analysis of Scientific Books. 



current of air entering at the valve ; and a striking experiment 

 with this apparatus consists in alternately shutting and opening 

 the air-valve, which is accompanied by the alternate appear- 

 ance and disappearance of the smoke. 



Even from this brief and incomplete view of Messrs. Parkes's 

 contrivance, it is obviously preferable, in some respects, to that 

 of Mr. Brunton : it is much less complex and expensive, and, 

 when properly and assiduously attended to, it effects a more 

 complete destruction of smoke ; but, on the other hand, its suc- 

 cess is infinitely more dependant upon the persons who manage 

 the fire, and whose dispositions are generally a mixture of 

 ignorance and prejudice, duly tempered with the warmth of the 

 element over which they preside ; we also doubt whether the 

 same unequivocal testimony can be adduced in respect to the 

 saving of fuel, for this again is more in the stoker's power. Ip 

 point of originality, too, Mr. Parkes must undoubtedly yield 

 the palm to Mr. Brunton ; he is anticipated in every part of his 

 invention by the words of Mr. Watt's patent; and we rather think 

 that Mr. Gregson, of whose method of constructing chimneys 

 an account will be found in a former Number of this Journal*, 

 has also touched upon some of the most important parts of his 

 contrivance. We, however, by no means state this opinion 

 with a view to detract from Mr. Parkes's merit ; on the con- 

 trary, if he has attained that in which Mr. Watt failed, the 

 nearer his means approach to those unavailingly employed by 

 his eminent predecessor, the more substantial is the service which 

 he has rendered the public, and the more praiseworthy the 

 perseverance by which he has accomplished his object. We 

 believe that Mr. Watt never affected to combine diminution in 

 the consumption of fuel with the destruction of smoke, and 

 that, on the contrary, with additional expense and trouble, 

 there were more coals burned; at least this is the only cause to 

 which we can refer the non-consumption of smoke, and the non- 

 application of his patent, in the greater number, if not in all, 

 the large engines of his erection which we have had occasion to 

 visit. 



One subject seems to us to have been overlooked by the ma- 

 jority of smoke-reformers, namely, the construction, and more 

 especially the height, of the furnace chimneys. By conveying 

 black smoke, and other pernicious fumes into a capacious and 

 very lofty chimney, much of the noxious matters that otherwise 

 escape into the atmosphere are decomposed and precipitated, or 

 condensed within ; we were much struck some years ago with 

 the effect of a long flue and lofty chimney attached to the 

 steam-engine of the Dartford Powder-mills ; scarcely any smoke 

 issued from its funnel, the fuliginous particles being almos.t, 



* Vol. HI. J.. 34R. 



