HMS Bullfinch
HMS Bullfinch
1868 One vessel of this name was built with engines by J. and G. Rennie
H.M. Torpedo Destroyer Bullfinch
Another vessel bearing this name, built c.1899 by Earle's Shipbuilding and Engineering Co.
1899 Full power consumption test. 'The required speed - 30 knots - had already been obtained. The run continued till about 1.10 p.m., the engines making about 300 revolutions per minute, and indicating 6120 horse-power. At the hour last named the connecting-rod of the starboard high-pressure cylinder broke, releasing the piston, which flew up and cracked the top cover, through which steam escaped. Messrs. Earle's manager, Mr. A. H. Tyacke, did all that he could, but unfortunately eight men were killed, and four others were seriously injured by the escaping steam. ...' [1]
1899 Report in The Engineer on the inquiry into the fatal accident when a connecting rod on the starboard engine failed at 390 rpm [2]. The investigation was unsatisfactory. The article in The Engineer noted that by design an unnecessarily large hole was bored through the length of the rods. It went into great length about the quality of the material, but offered no analysis of stresses, and showed no real appreciation of metal fatigue, although there was an awareness that high alternating stresses may have been involved, the second article in The Engineer concluding: 'Finally, the fact that the low-pressure rods are quite sound is irrefragable proof that the rods which broke were not strong enough to do their work. There seems to be some reason to believe - and this is a most important matter - that when steel is submitted to vibratory or concussive stresses it is not trustworthy, however excellent it may be at first, unless the load is very light. Thus the high·pressure rods of the Bullfinch might be of superlatively good steel, and loaded very lightly as compared with the testing·house stresses, and yet be much too weak for the totally different class of stresses to which they were submitted on board the Bullfinch.' [3]
1902 The case of the failed connecting rod came up again, in connection with an insurance claim. [4]. Various experts gave evidence, including Professor Ewing, who evidently did appreciate the fatigue aspect, and was reported as stating that '.... The limit which alternating stresses should not exceed was about one-third of the tensile breaking strength, and he thought that if the maximum stress in the jaw were 40,000 lb. per square inch it must necessarily have produced fracture after some thousands of alternations of stress. If the stress were below 40,000 lb. the number of alternations would naturally be greater. He had not seen any satisfactory evidence that the trellis-work structure per se and apart from the question of size, was at all prejudicial. ...'. The mention of the 'trellis-work structure' refers to a statement made by Prof. Arnold. </ref>