4G0 Om Woolf's Sieam-Engwe. 



phry Davy's discovery flowed from science judiciously applied. 

 Stephenson's discovery appears to have resulted from trials made 

 below ground ; for, though an excellent mechanic and acute 

 man, he is unacquainted with the science of chemistry. Thus a 

 great object has been obtained in rendering the occupation of 

 the coal miner in this part of the kingdom less hazardous from 

 the dreadfid effects of inflammable air ; and I hope you will not 

 think the pages of your valuable journal misapplied in giving pub- 

 licity to a contrivance, by which the lives of hundreds may be 

 saved in other coal-mining districts, as well as on the banks of 

 Tyne and Wear. 



Nfcucastle, Dec. 10, 1815/ N. 



Explanation of Mr. Stephenson's Lamp for Miners. 



(Fig. II.— Plate VIII.) 



A. The lamp made of copper. 



B. The glass chimney. 



C The perforated tin cover. 



d d d d. Air holes. \ 



E. Wick tube. 



?. Oil tube. 



LXXXIV. On Woolf's Steayn Engine ; loith Certificates of 

 their Pejformance, from the Managers of the Mines in 

 Cornwall where they are at work. 



To Mr. Tilloch. 



Sir, — JTJLaving observed with pleasure for several months past, 

 in the Philosophical Magazine, a statement of the duty per- 

 formed by the different sorts of engines at work pumping water 

 out of the mines in Cornwall ; and presuming that the effect 

 roust have been to excite a more general interest in favour of 

 Woolf's engines; we transmit for insertion copies of two certifi- 

 cates from the agents of the mines where they are at work ; to 

 which it seems needful to add, that the very great quantity of 

 cofd represented to be saved by the use of Woolf's engine at 

 Wheal Vor, is in some measure to be attributed to the indifferent 

 state of the one pumping water on Boulton and Watt's plan. 

 WoolFs engine is, however, doing the same duly as is usually 

 done by good engines on Boulton and Watt's plan, with less 

 than one half the quantity of coal. 



From the facts exhibited practically by the engines we have 

 made on Wooli's plan, vvc do not hesitate to give it as our opi- 



