which forms in the Boilers of Steam- Engines. 253 



the multifarious works to which steam-power is now applied. 

 These incrustations will of necessity be very variable, both 

 in quantity and quality, according to the kind of ingredients held in 

 solution in the water used for generating the steam. Hitherto I 

 have examined two specimens only of incrustation taken from the 

 boilers of locomotive engines, and a single one only from the boiler 

 of a steam-engine employed on a mine — a mine in the west of Corn- 

 wall. The latter was fibrous, about half an inch thick, and consisted 

 chiefly of sulphate of lime, with a little silica and peroxide of iron, 

 and a trace of fluorine. The former were from one-tenth of an inch 

 in thickness to one inch. They were laminated, of a grey colour, 

 and had much the appearance of volcanic tufa ; they consisted prin- 

 cipally of carbonate and sulphate of lime, with a little magnesia, 

 protoxide of iron, silica, and carbonaceous matter, the last two, the 

 silica and carbonaceous matter, probably chiefly derived from the 

 smoke of the engine and the dust in the air. From the engineer's 

 report, it would appear that the thinnest — the incrustation of about 

 one-tenth of an inch — had formed in about a week, during which 

 time the locomotive had run about 436 miles, and consumed about 

 10,900 gallons of water. 



Bemarks on a Bone Cave near the Mouth of the North Esk. 

 By Mr Alexander Bryson. Communicated by the 

 Author. 



This cave was discovered three years ago by Mr James Walker, 

 the intelligent tenant of the farm of Nether Warburton, while re- 

 moving alluvial debris from the north bank of the North Esk. It 

 is situated within a mile of the confluence of that river with the 

 German Ocean, and twelve feet above its highest spring-tides. The 

 rock in which it occurs, is amygdaloidal trap enclosing cavities in 

 which are found decomposing zeolites. Its distance from the nearest 

 part of the channel of the North Esk, is about 400 yards. The 

 mouth of the cave being laid bare by Mr Walker's operations, he 

 found it filled with debris, containing a vast assemblage of the bones 

 of the smaller animals (mostly rodentia.) On probing it by means 

 of a long pole, it was found to extend upwards in a sloping direction 

 parallel nearly with the incHnation of the bank, to a height of 15 

 feet. Being desirous of investigating the interior of the cave, with 

 the assistance of a friend we enlarged the opening to permit our ascent. 

 On entering, I found the cavity presented the usual appearance of 

 caves in trap-rocks, where the exterior crust, from the shrinkage 

 below, forms an arched roof. The mouth of the cave on the occasion 

 of our visit, was entirely filled with soil richly stored with the bones 

 of the ox, deer, badger, hare, rabbit, and other smaller rodents, also 

 with a few bones of birds. The manner in which these remains were 

 deposited, left no doubt that the agents had been the waters of the 

 North Esk. 



