"It is needless to repeat instances of much the same kind, as occurring during the experiment referred to. The author is bound to say that they were, no doubt, influenced by the favorable circumstances of weather, and something is to be allowed also for the great length of train drawn, very long trains having a less tractive resistance per tun on a level than short ones, and something, possibly more than is commonly supposed, may have been due to the use of oil-tight axle boxes, the saponaceous compound known as 'railway grease' being nowhere in use on railways in the States. It could not possibly be used, except in a congealed form, in the severe American winters; and Messrs. Guebhard and Dieudonné's experiments (_vide_ "De la résistance des trains et de la puissance des machines." 8vo. Paris, 1868, p. 36) made in 1867, on the Eastern Railway of France, showed a very considerable diminution in the resistance of oil-boxed rolling stock as compared with that fitted with grease boxes. But, weighed upon the other hand, are the facts, first, that the line was of 6-feet gage, and, _pro tanto_, so much the worse for traction; secondly, that the wheels were comparatively small, and the inside journals of comparatively large diameter, the ratio of the former to the latter being as 7¾ to 1, instead of 12 to 1 as on English lines. It is difficult to believe that the length and steadiness of the double bogie goods wagons, scarcely liable as they are to lateral vibrations, had not something to do with the result, which is in some respects unique in the history of railway traction. The result, although not absolutely showing the real resistance to traction, nor the real adhesion of the engine, presents this alternative; namely, that the resistance must have been unusually small, or the adhesion unusually large." In the discussion which followed some doubts were expressed as to the accuracy of Mr. Colburn's conclusions, drawn from the experiments described; but it was conceded by some who took part in the discussion that some of the features of our practice might be advantageously copied in England. For the most part, however, the opinion prevailed that the features of our system, which are here regarded as almost indispensable, could not be introduced into English practice with advantage. * * * * * BOILER COVERING. BY C.M. O'HARA, C.E.