3*9 



spread over the layer of rougher stuff first put on. Fine sand or 

 gravel must then be sprinkled freely over the top of this, and 

 the whole once more rolled, or beaten fiat with the back of the 

 blade of a spade, if no roller be available. General Building Art 

 and Practice. 



CONCRETE PAVEMENT This is far cleaner to work than tar 

 pavement, and is put down in the following manner : The earth is first 

 taken off the surface of the path to a depth of 8 in. or 9 in., and the 

 shallow trench thus made is rilled up to about two-thirds or three- 

 fourths of its whole depth with stones, broken brickbats, and coarse 

 gravel, well rammed together so as to present a level surface. The 

 Portland cement must now be mixed in a tub with \vater until it is 

 of the consistence of thick cream or custard, and poured over the 

 gravel. This must be spread about with a bast-broom to level the 

 surface and send it into the interstices of the first rough coat of 

 stones and gravel. On this a coating of Portland cement and 

 gravel, mixed with water, must be spread, bringing the service very 

 nearly up to the height of the path ; and when this has hardened, 

 a finishing coat must be put on of clean, sharp sand and Portland 

 cement in equal parts, and brought, when mixed with water, to 

 the consistence of mortar. The surface must be rounded and 

 brought to smoothness by the aid of a float, a piece of wood with 

 a handle at the back, something like a laundress's iron, but longer, 

 with which plasterers finish the surface of walls and ceilings. No 

 one should be allowed to tread on the surfaces thus made until it 

 is perfectly dry and hard. General Building Art and Practice. 



TRACTIVE FORCE OF HORSES. 



Rate in miles per hour 2 2\ 3 3^ 4 \\ 5 



Tractive force exerted in Ibs. ... 1 66 150 125 104 83 62 41 

 Force of traction required for carriages of one ton on a level road : 



Description of road. Force of traction per ton. 



1 On rails 8 Ibs. 



2 Well made pavement ... ... ... ... 33 ,, 



3 Macadamised road ... ... ... 44 to 67 ,, 



4 Turnpike, hard and dry ... ... ... 68 ,, 



5 dirty 88 



6 Hard compact loam ... ... 119 ,, 



7 Gravel ... ... ... ... ... ... 150 



8 Sandy and gravelly ... ... ... ... 210 



9 Ordinary bye-road ... ... ... ... 237 



10 Turnpike, newly gravelled 320 



n Loose sandy road 457 



A horse produces his greatest mechanical effect in drawing a load 

 at 2\ miles per hour with a tractive force of 150 Ibs. 



