-The London giueetr states thit the highest railway speed in the world are attained in Engl'Biid, d that th highest of all is reached on the Grettt Western Railroad - the speed on the latter being given roundly as fifty miles an hour, and the Enginter believes that it would be possibl to lay permanent wny so well, and to mflintain it in such excellent order, that trains tnight travel on it witb. perfect gafety at one hundred miles an hour indeed, miles upon miles of such tracks are now to be found on most of the great muin Unes, but nowhere can one hundred consecutivo miles of permanent way in perfection be found ; and, as a chain ig no stronger than its weakest link, go a few hundred yarda of bad track would spoil for the parpóse of traveling at one hundred miles an hoir the whole line. The really important question, argües the Knginecr, is, given tl. e line and cars fit for it, what shall the engine be lifce, and ia it possrible to construct an engine at all whioh, with a moderately heavy train, vill att.ain uul maintain a velooity of one hundred miles mi hour, on a lino with no njradi hcavier Uien, say one in throe hundred. Aftei a thorough examination of the question in all its liearings, tho Enginetr' figuros prove that it Í8ibsolutt!ly impossible to obtain a speed of one hundred miles an honr on a railway, if the resistance is anything like onehundrod and twenty pounds per ton.