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MODERN STEAM PRACTICE.

Some may say this cannot always be done, so as to give a boilerof a certain diameter. We will only remark that if the plates willnot run evenly, an inch more or less does not affect the diametervery much, as likewise the length of the boiler is not generally soconfined. The object of even dimensions is simply that when theplates arrive they are at once taken to the planing machine to havethe edges planed, and then they are punched or drilled, as the casemay be, the punching machine being provided with a travellingtable, moved along by hand, the table having suitable stops, thusthe machine templates or sets out the holes and punches at one andthe same time. Now this could not be done if the plates wereordered of uneven dimensions. Those who have not adopted thisplan for plating for all kinds of boilers cannot be aware of thegreat saving effected. We have known working drawings goinginto the workshop, and the boilers have been plated haphazard,stock plates being kept for that purpose. We may at once notethis plan a complete barbarism. Plates should be ordered foreach boiler separately, and properly marlced both on the drawingand on the plates as delivered from the rolling mills, when theyshould be assorted, and the workman then knows where to lay hishand on No. i or No. 13 plate, as the case may be. By this rulebeing duly attended to much saving is effected. Indeed, a prac-tised eye can at once detect when boilers are plated haphazardor regularly; and certainly it is not very pleasant to be told thatthis or that boiler has not the same appearance, owing to theirregularity of the plating as taken from stock; and great wasteoccurs when plates require to be cut down to suit a particular boiler.

For all difficult boilers block models should be made, and all theplates set out and marked, so that the workmen can see at a glancewhat the work consists of, the model giving a better idea than adrawing, and also Standing more rough handling;—the drawing, insome cases, never being required in the workshop.

All the plates should be ordered for planing the edges; % of aninch is the regulär allowance for doing so, not that so much is requiredto be planed off, but at times the plates are not so square at thecorners as can be desired. This method of planing the edges savesa great deal of chipping, and the joints are more easily caulked.

In plating the boiler care must be taken so that the flame does notact on the edges of the plates. All joints should be so laid that theflame passes over, and does not impinge against the end of the