SCIENTIFIC SUMMARY. 
99 
Fossil Fishes of Carinfhia . — ^Herr Kner lias issued a supplementary list of 
tlie fossil fishes of Carinthia. In this he describes a species (Pterycopterus 
ospus'), which is provided with wing-shaped pectoral fins, and which forms 
the type of a new genus allied to Thorecopterus. 
The Flint Implements of Treiche . — In a description of the ancient flint 
implements foimd at Treiche, near Toul, M. Guerin states the following 
opinions : — I. The Plateau of Treiche, on a surface of at least fifty acres, 
was the seat of a sort of manufactory of flint implements of the same 
antiquity as those of Grand-Pressigny. 2. These weapons are older, judging 
by their form and finish, than those of the Caves of Sainte-Reine. 3. The 
flints found here are of the diluvian class, and are very small. 
MECHANICAL SCIENCE. 
British Association . — Amongst the "papers read before the Mechanical 
section of the British Association we may record as of permanent importance 
that by Mr. John Platt, of Oldham, on cotton machinery ; the collection of 
tables of steamship performance and report thereon, by a committee of the 
Association ; the E-ev. Mr. Bell’s narrative of the invention of the reaping 
machine ; and Mr. Bateman’s account of the Manchester waterworks. 
Strength of Steel. — Dr. W. Fairbairn, F.B.S., has published a very valu- 
able series of researches on the tensile, transverse and compressive strength 
of steel of various qualities. The mean value of the modulus of elasticity 
obtained was 31,000,000 lbs. ; the minimum 22,098,000 lbs. the maximum 
32,672,000 lbs. The value of the modulus of resistance to transverse strain 
at the elastic limit (or resistance of bar 1 inch long and 1 inch square) varied 
from 3T08 to 7'856 tons. The tenacity varied from 26*57 to 59*87 tons per 
square inch. From the experiments on transverse strain Dr. Fairbairn con- 
cludes that the cost of railway bars and similar structures of iron and steel 
is in the ratio of 1|^ to 1 for equal strengths, irrespective of the greater 
durability of steel, and taking the price of steel at 12/. and of iron at 71. 
per ton. The importance of this deduction cannot be over-estimated at a 
time when the great durability of steel rails is exciting so much 
attention. 
Slide Valves. — Mr. J. B. Napier and Professor Rankine propose to remove 
the obj ection to the slide valve and link motion as a means of obtaining a 
variable rate of expansion, by making the seat of the valve moveable. The con- 
venience of the link-motion with a single valve is well known, but when used 
to cut ofi‘ the steam at variable points in the stroke an objection arises from 
the fact that the points of admission, cut off, release, and compression are 
so related, that fixing any three of these positions fixes the fourth also ; and 
it often happens that the best positions of release and of compression are 
inconsistent with each other, so that a compromise has to be made. This 
objection is proposed to be obviated by giving a small sliding motion to that 
part of the valve seat which contains the induction edges of the cylinder 
ports, so as alternately to contract and enlarge those ports at each stroke of 
the engine. The valve seat is moved by a rod and third eccentric. It need 
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