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equalized, the total breadth of both side walls, where in contact withthe plates, need not exceed I inch for every foot of diameter of theboiler. The top of the side flues should be level with the crown ofthe flue tube. All boilers should be roofed over to protect themfrom external moisture, otherwise the sides in contact with the fluebrickwork will be weakened by corrosion. Where flues are properlyarranged as described, no serious corrosion could exist in the seatingsundetected by a skilled inspector. The laws for the prevention ofsmoke are now being enforced in many districts, but boiler-ownersshould be cautioned against too readily adopting any form of appar-atus which may be pressed upon their notice, as many are unneces-sarily complicated and expensive.
“ It frequently happens that good boilers are injured and seriousrisk is incurred through neglect and carelessness. Where the feedwater contains much Sediment, and no cleaning apparatus is in use,frequent internal cleaning is indispensable, or the plates may becomeoverheated and injured, whilst the efficiency of the boiler is reduced.The external flues are in many cases allowed to become almostchoked before being cleaned, and the boiler plates so thickly coatedwith soot, that awasteful consumption of fuel is the result. Some firms,on the other hand, clean their boilers thoroughly about once a month,and are thereby considerable gainers, as the efficiency of the heatingsurface is retained, whilst any defects are at once discovered andmade good, which, if neglected, might entail expensive repairs, oreven lead to serious disaster. When boilers are being restarted afterstoppage, they should be heated very gradually, so as to avoid, asmuch as practicable, the severe strains of unequal expansion, andwhen at work the feed supply and the firing should be as steady andregulär as possible. Frequent and extreme alterations of pressure,especially with high-pressure boilers, or irregularity of any kind, ismost objectionable, and sometimes really dangerous.”
We consider the foregoing remarks are well worthy the consider-ation of steam users, although we do not entirely agree with thewriter in limiting the length of land-boilers to three and one halftimes the diameter; and we do not advocate too thin plates forflues, even though stayed with hoops, although the flues are therebystrengthened; but entirely agree with him that conical water tube-stays are invaluable for staying the flues, as deposit is not liable toform, as is the case with the hoops. We have known many instanceswhere deposits have rapidly formed at the roots of the hoops,