Miscellaneous Intelligence. 139 
tent far exceeding that to which the economy of the steam-engine is 
restricted ; and the more fully, in short, shall we accomplish that which 
has hitherto been very imperfectly done—to REALIZE THE ADVANTAGES 
OF THE AIR-ENGINE. 
The fourth section describes the improved air-engine of Messrs. James 
d J.M In thi 
e e 
the degree of condensation at which the air is employed. e air re- 
ceivers of an experimental engine were completed some time since, 
without practical difficulty, notwithstanding the novelty of their con- 
struction ; but the erection of the engine has been retarded by delay 
in the execution of the cylinder, fly-wheel, shaft, and other parts, which 
are similar to those of a steam-engine. 
Independently of the amount and value of the saving of fuel, which 
will result from the introduction of the air-engine, it possesses the im- 
portant and incontestable advantage, that even should an air receiver 
burst (which is very unlikely), the explosion would be harmless, for its 
force would not be felt beyond the limits of the engine itself. Red-hot 
air does not seald.—Proc. Brit. Assoc., Sept., ; 
2. On Lightning Conductors, (Proc. Brit. Assoc., Athen., No. 
1405.)—Mr. Nasmyrn described a Lightning Conductor for Chim- 
fore safer than those in common use. e present practice is to fix 
the conductor outside the chimney by metal holdfasts, by which means 
Supports fixed on the top. A conductor of this kind had proved e 
cient in storms which had severely injured other sie we in the neigh- 
borhood that were protected in the usual manner. n experience of 
eighteen years had tested the superiority of the plan. 
Prof 
pay, on being called on for his opinion, said that he re- 
