678 
MU. FAIRBAIRN’S EXPERIMENTAL INQUIRY 
And lastly. On the strength and value of wrougbt-iron frames and ribs as applied 
to ships and other vessels*. 
PART I. 
At the commencement of iron ship-building’, in which I took an active part, the 
absence of acknowledged facts relative to the strength and varied conditions under 
which the material was applied, was the principal reason which induced me to enter 
upon this inquiry. I have extended the investigation into the best methods of rivet- 
ing, and the proportional strength of rivets, joints, &c., as compared with the plates 
and the uses for which they are intended. The latter is a practical and highly im- 
portant inquiry, as great difference of opinion exists amongst engineers and others, as 
to the form, strength and proportions of rivets, and the joints of which they form an 
essential part. I therefore considered an experimental investigation much wanted, 
not only on account of its important practical bearing, but what was probably of 
equal value, in order to remove existing discrepancies and to establish a sounder 
principle of construction founded upon the unerring basis of experiment. From these 
considerations I bestowed increased attention upon the inquiry, and endeavoured to 
render it practically useful. Before detailing the experiments, it may be necessary 
to describe the apparatus by which the results were obtained. 
The annexed drawings, Plate LIV., represent a side and end view of the apparatus 
used in the experiments. The large lever A was made of malleable iron and was fixed 
to the lower cross beam B (fig. 1) by a strong bolt O, which passed through it at B. 
At the top end of this bolt a preparation was made to receive the end of the lever, 
and by means of the screw-nut at a, the lever A was raised or lowered to suit the 
length of the plates to be experimented upon. Upon the top side of the beam, and 
under the gable wall of a building five stories high, were placed two cast-iron columns, 
D, D, which retained the beam B in its place and prevented it from rising when the 
lever was heavily loaded during the experiment. The frame E guided the end of the 
lever and the weight W, and close to the fulcrum were placed two wooden standards, 
* Several important facts and improvements in the construction of iron ships have been ascertained since my 
experiments were made, hut I apprehend none of them have tended in the least degree to diminish their 
value. Nor have they, to the best of my knowledge, been superseded by others of a more elaborate or more 
decisive character. It is true, that a series of interesting and important experiments have been made at the 
instance of the Admiralty on the effect of shot upon the sides of iron ships. At some of these experiments I 
had the honour to be present, and witnessed some curious and unexpected results. 
The first series was conducted at the Arsenal, Woolwich, and subsequently others were made at Portsmouth. 
Both were important as respects the effect of shot upon w'rought-iron plates, with enlarged and diminished 
charges of pow'der and at different velocities, but discouraging as regards the use of iron in the construction of 
ships of war. These e.xperiments, however interesting in themselves, do not appear to be conclusive ; and it is 
to be hoped that the apparent danger, indicated by the experiments, may yet be overcome, and the superiority 
as well as the greater security of the iron ship fully established. 
