342 IMPROVEMENT IX RAIL ROADS. 



Description of The usual length of a tram-plate is three fect^ the flancrt 

 and method of or outside edge II, about one inch and half high, the sole or 

 »aking rail bed I, from three inches and a half to four inches broad, 

 and three fourths of an inch thick ; but these dimensions 

 may be varied according to circumstances. The most ap- 

 proved weight has been 14 pounds to the foot, or4 ( 2 pounds 

 to the plate, the ends from which the plugs project, and to 

 which the tenons and mortises fasten, should be one fourth 

 of an inch thicker than the other part of the plate. 



Fig 3. A B show r the under part of the tenon and mortise, 

 and the form of one of the sloping or bevel plugs. 



The diameter of the plug near the shoulder is one inch 

 and three quarters, reducing to one inch, its length two 

 inches and a half, forming an angle of eight degrees, the 

 plate from which it projects is counter sunk, so that the 

 shoulder of the plug may not receive any sharp pressure or 

 prevent the plate from having a perfect bearing. There is 

 a small groove in the whole length of the exterior of each 

 plug, to admit a wire to pass to its extremity, to draw the 

 plug out if broken by any accident, also to admit the ex- 

 pansion of water, in case of severe frost. 



The blocks or sleepers, E F G, on which the tram-plates 

 are piaccd, should by no means be less than 120 pounds 

 each in weight, but should be heavier on some kinds of 

 ground ; the depth of the hole for the plug should be three 

 inches, and worked according to the inclination of the 

 plug, for which purpose the stone-mason should have a 

 standard cast-iron gauge ; there should be projections, K, 

 cast with the flanch or outside edga of the tram-plate, as 

 shown at fig. 1, to make the plates lie firm on their sleepers. 

 Fig. 4 is a section of one of the ends of a tram-plate, 

 in which H shows the ilanch or upright edge, I the flat part 

 or sole on which the wheels of the waggons run, D one of 

 the plugs, K the projection behind the flanch to make the 

 plate lie firm on the blocks 



GENERAL OBSERVATIONS. 



.Adtantapes of The advantages of laying plates on the above principle 

 this compaMd arc () j )Y j ons . the blocks being put in their places never sink 

 moil mode. below their intended levd, the act of driving either nail 



or 



