438 
POPULAR SCIENCE REVIEW. 
pair of wheels, such railways might he constructed for 3,000/. to 3,500/. per 
mile of single way. Mr. Lawford described a short line of this description, 
constructed for the Duke of Buckingham and Chandos at Wooton. This 
line, of 6 miles in length, with a branch of miles, is essentially a surface 
line, the highest embankment being 12 ft. and the deepest cutting 10 ft. 
Turnpike and other roads are crossed on the level. The rails are 301b. 
bridge rails on longitudinal timbers. The ballast is 10 ft. wide and 6 to 
9 in. thick under the sleepers. 
Compound Engines of the u Tenedos .” — In the recent trial of the engines 
of the u Tenedos,” the consumption of fuel, in the six hour runs, varied 
from P58 lbs. per I. H. P. per hour, at eight-knot speed, to 2-32 lbs., at 
thirteen-knot speed. The rate of expansion of the steam was 9 times 
in the former case and 6^ times in the latter case. These results are ex- 
tremely satisfactory. 
Water Power. — The Industrial Society of Mulhouse has recently received 
communications about a project for utilising the fall of the Phone at Belle- 
grande. According to the calculations of M. Colladon, of Geneva, this fall 
of thirteen metres could be utilised so as to afford 10,000 horses power. An 
American company, employed in the production of phosphate of lime, pro- 
poses to construct a tunnel for utilising this fall, and offers to Alsatian 
manufacturers to erect at Bellegrande establishments similar to those they 4 
possess at present. (Paris Correspondent of Engineering.) 
Self-acting Rudder. — At the International Exhibition of Naples, Signor 
Siciliano, of Palermo, exhibited an arrangement for working the rudder 
of a ship by means of electro-magnets. The currents which actuate the 
electro-magnets are under the control of the ship’s compass, any deviation 
of the compass from an assigned direction completes an electric circuit, 
which in turn, through the electro-magnets, acts on the rudder. Thus the 
compass and rudder form a perfectly automatic arrangement. 
MEDICAL. 
Volumes of the Cavities of the Heart. — Professor the Pev. Samuel Houghton, 
E.P.S., in his recent lecture (June 24) before the Poyal Institution, at- 
tempted to compute the volumes of the ventricles of the heart. Admitting 
the principle of least action, he said : u I can predict a thing that at first 
sight appears very strange. I can find the ratio which the volumes of the 
two cavities bear to each other by the measurement of the lengths of the 
fibres that surround them. On measuring these fibres it comes simply to 
this. Let l be the length of the fibres that go round the entire heart : let / 
be the length of the fibres that go round the left ventricle. Eind those 
lengths and cube them. The ratio of those cubes will be proportional to 
the sum of the right and left ventricles divided by the left. There are 
theoretical grounds which I believe are almost of themselves sufficient to 
entitle us to believe that these two cavities are of equal volume, and there- 
fore that this fraction will come out equal to 2. I have taken, however, a 
more certain mode of determining this by collecting together all the obser- 
