Polytechnic Association Proceedings. 683 



improvement in the blast furnace. 

 A French journal states that M. Morgan has increased the pro- 

 duction of iron in furnaces six-fold, by giving them greater dimen- 

 sions; for instance, nine and a half meters diameter (nearly thirty 

 feet), and blowing into them by twelve tuyers. A hollow cone is 

 also constructed in the middle of the furnace, through which 

 another blast is introduced. 



, VELOCIPEDES. 



This carriage, which is simply a saddle sustained before and 

 behind by a large light wheel, and at such a height that the rider 

 may use his own feet as propellers, has again been brought into 

 use in Paris. Many amateurs who are fond of this sort of violent 

 exercise, have selected the vicinity of the cascade in the Bois de 

 Boulogne, where the}'^ may be seen usually between the hours of 

 nine and eleven, showing their sldll and testing their comparative 

 speed. 



CROMLECH. 



M. de Closmadeuc has discovered, in a small desert island in the 

 Bay of Mor])idan, France, a very fine cromlech containing more 

 than sixty obelisks of granite, forming a regular circular of one 

 hundred and eighty meters in circumference. A curious fact is, 

 that only one-half this cromlech, which is supposed to have been a 

 Druidical altar, is now on dry land, owing to the encroachment of 

 the sea. M. de Closmadeuc, has made large excavations in the 

 neighborhood, and discovered an enormous quantity of pottery, 

 similar to that found in Celtic monuments; several hundred flints 

 worked by man, as well as a large number of stone hatchets, 



SAFETY LiVMPS. 



Mr. Hutchinson, manager of the Barnsley Gas Works, and Mr. 

 Wilson, steward of the Darfield Main Colliery, have recently tested 

 the relative value of diflerent kinds of safety lamps when exposed 

 to a current of air and explosive gas. Their apparatus consisted 

 of a rectangular box about twelve feet long, and eleven inches by 

 four inches inside, attached to the flue of the retort-house chim- 

 ney, the draft being three-tenths of an inch as indicated by a 

 water-gauge, and the velocity of the current of air being at the rate 

 of five miles an hour. The several lamps to be tested Avere in suc- 

 cession placed at one end of the box, and at the other was a glass 

 sight-hole for the purpose of watching the operation. A stream of 



