260 



Sir W. Fairbaim on the Durability and [Apr. 24, 



corrosion of the Menai Bridge. The author on that occasion visited the 

 bridge, and found that no corrosion had taken place, careful attention to 

 proper means of prevention having been sufficient to preserve the struc- 

 ture. The proved value of periodical inspections in the case of steam- 

 boilers is then alluded to, and the author urges the importance of similar 

 inspections of iron ships by the Admiralty and by private shipowners. 



As respects riveted joints, the author first discusses the relative merits 

 of machine- and hand-riveting, and points out that in machine-riveting 

 there is much greater security that the rivets properly fill the rivet-holes. 

 The rate at which riveting can be done is given as 16 rivets per minute 

 with a lever riveting-machine, 10 rivets per minute with a steam rivet- 

 ing-machine, and 066 rivet per minute when the riveting is done by 

 hand. 



Experiments on Biveted Joints. 



The author alludes, first, to the series of experiments on riveted joints 

 which were communicated by him to the Eoyal Society in 1850. Those 

 experiments showed that, taking the strength of a solid plate at 100, the 

 strength of an equal width of riveted joint would be 70 if the joint were 

 double riveted, and 56 if the joint were single riveted : in other words, 

 30 per cent, of strength is lost in a double-riveted joint, and 44 per cent, 

 in a single-riveted joint. Since that time it has appeared to some 

 engineers that the process of punching was injurious to the plates, and 

 in many cases recourse has been had to drilling to form the rivet-holes. 

 On this point the author was of opinion that with good iron no sensible 

 injury resulted from punching the rivet-holes ; on the other hand, with 

 rigid and bad plates, the plate would crack between the rivet-holes, and 

 the plate would have to be discarded. He regarded it as a distinct 

 advantage of the punching-process that it thus tested the quality of the 

 iron. It had been found in certain cases that the rivets sheared across 

 with a less force when in drilled than when in punched holes, and this 

 had been attributed to the sharpness of the edges of the drilled holes. 

 This point seemed to require investigation, and experiments to elucidate 

 it had, therefore, been made, the results of which are narrated in the 

 paper. The theory that the sharp edges of drilled holes induced a 

 cutting action, which diminished the strength of the rivets, had suggested 

 to Colonel Inglis, R.E., to try whether a greater resistance in the joint 

 could be obtained by purposely rounding the edges of the rivet-holes. 

 Some experiments had been made for Colonel Inglis by Mr. Kirkaldy, 

 from which it appeared that the resistance of the rivet was increased 10 

 per cent, by this rounding of the edges of the rivet-holes. The author 

 has also experimented on this point, and the results of his experiments 

 are given in the paper. 



A series of tables of experiments are then given, each result being 

 fully discussed. The following Table is a summary of results obtained 

 by the author. 



