132 Description of improved Tram-Plates 



vents the others from moving, and when taken np- releases 

 all those between the stop-plates ; 25 yards of rail road made 

 with these plates, may he taken up and replaced within ten 

 minutes. The plugs in dotted lines are shown in their pro- 

 per positions within the sleepers EFG. 



The usual length of a tram-plate is three feet ; the flanch 

 or outside edge H, about one inch and half high ; the sole 

 or 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 approved 

 weight has been 14 pounds to the foot, or 42 pound's 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. 7. A B, Show 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 

 ruches 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 pe feet 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 

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

 pansion of water, in case of severe frost. 



The blocks or sleepers, EFG, on which the tram-plates 

 are placed, 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 edge of the tram-plate, as shown at 

 iTg. 5, to make the plates lie firm on their sleepers. 



Fig. S. Is a section of one of the ends of a tram-plate,- 

 in which H shows the flanch or upright edge, I the flat 

 paTt or sole on which the wheels of the waegons run, D one 



of 



