610 
SECOND REPORT—1832. 
The price of bar iron in Vienna, when I left it, (about a year 
since,) was 6/. a ton; that of bar steel, formed from the decar¬ 
bonized cast iron, 8/. 16s. 
By means of the Styrian steel, suspension-bridges may be 
built for less than half the cost at which they could be formed 
of iron; and a span of double the extent that would be prac¬ 
ticable in iron, may safely be ventured on in steel. I have cal¬ 
culated that upwards of 1000 feet span may with confidence 
be depended on. 
Mr. Hawkins likewise exhibited a specimen of the sand em¬ 
ployed in the fine iron castings at Berlin. 
The Rev. William Taylor exhibited a variety of specimens 
of Ornamental Turning, such as is usually attempted with the 
rose engine, but executed by himself with the common milling 
tool, and slight modifications thereof. 
Abstract of Researches on the Strength and best Forms of Iron 
Beams*. By Eaton Hodgkinson. 
If a beam be fixed at one end in an horizontal position, and 
be bent or broken by a weight at the other, it is evident that 
the upper fibres will be extended, and the lower ones com¬ 
pressed; and therefore there must be some intermediate part, 
which will neither be extended nor compressed. This bound¬ 
ary has been denominated the neutral line, and its position is 
always dependent on the following equality:—The sum of the 
forces exerted by the extended fibres is equal to the sum of 
the forces from the compressed fibres...(1.) We have, more¬ 
over, from the principles of statics,—The product of the weight 
at the end of the beam by the length of leverage equal to the 
sum of the moments of the forces on both sides of the neutral 
line, with respect to that line... (2.) 
If the forces of tension and compression are known, and the 
situation of the neutral line be obtained in any one form of 
beam, we may, by equation (1) above, find its place in a beam 
of any other form; and the strength of the beam itself by equa¬ 
tion (2). 
The theory from equations (1) and (2) is general, whatever 
the forces of tension and compression may be ; but its utility 
and accuracy are diminished when the beams are overstrained ; 
* A full account of these researches has been published in the 5th volume of 
the Memoirs of the Literary and Philosophical Society of Manchester. 
