During the recent visit of the Shah of Persia to England, he visited, among other places, the great works of John Brown & Co., at Sheffield, and witnessed the pressing of a propeller shaft for one of the large ocean steamships.  The operation is admirably illustrated in our engraving, for which we are indebted to the Illustrated London News.

[Illustration:  Propeller shaft being pressed at Messrs.  John brown & Co.’S works, Sheffield.]

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CRANK AND SCREW SHAFTS OF THE MERCANTILE MARINE.[1]

By G. W. Manuel.

    [Footnote 1:  A paper read before the Institute of Marine
    Engineers, Stratford, 1889.]

Being asked to read a paper before your institute, I have chosen this subject, as I think no part of the marine engine has given so much trouble and anxiety to the seagoing engineer; and from the list of shipping casualties in the daily papers, a large proportion seem due to the shafting, causing loss to the shipowner, and in some instances danger to the crew.  My endeavor is to put some of the causes of these casualties before you, also some of the remedies that have tended to reduce their number.  Several papers have been read on this subject, chiefly of a theoretical description, dealing with the calculations relating to the twisting and bending moments, effects of the angles of the cranks, and length of stroke—­notably that read by Mr. Milton before the Institute of Naval Architects in 1881.  The only practical part of this paper dealt with the possibility of the shafts getting out of line; and regarding this contingency Dr. Kirk said that “if superintendent engineers would only see that the bearings were kept in line, broken crank and other shafts would not be so much heard of.”  Of course this is one of those statements made in discussions of this kind, for what purpose I fail to see, and as far as my own experience goes is misleading; for having taken charge of steamers new from the builders’ hands, when it is at least expected that these shafts would be in line, the crank shaft bearings heated very considerably, and continued to do so, rendering the duration of life of the crank shaft a short one; and though they were never what is termed out of line, the bearings could not be kept cool without the use of sea water, and occasionally the engines had to be stopped to cool and smooth up the bearing surfaces, causing delays, worry, and anxiety, for which the engineer in charge was in no way responsible.  Happily this state of what I might call uncertainties is being gradually remedied, thanks being largely due to those engineers who have the skill to suggest improvements and the patience to carry them out against much opposition.