C2 



Hook gravel, and before this two inches of surface gravel is worn out 

 the drives will require to be surfaced with fresh material. Continued 



and careful observations have been made on the drives with the rub- 

 ble foundation, in order to compare them with those having Telford 

 foundation, and they have been found to compare favorably with them. 

 The road gutters have been constructed almost exclusively of stone 

 blocks similar to Belgian blocks, and laid upon a bed of sand one foot 

 deep. They are much less expensive than the brick gutters, will be 

 equally as durable, and will be much more easily repaired. There is 

 but one serious objection to them, and that is that a large amount of 

 surface w T ater is lost by passing between the blocks, and thas into the 

 ground. At this time, this is immaterial, as there is an abundant sup- 

 ply of pure water for the lake with its present area, but when the 

 lake is completed it will be advisable to- save all of the surface water 

 possible, in order to keep it supplied ; but the probabilities are that the 

 line silt worked from the roads will, before that time, so effectually 

 close up the crevices between the stones that almost no water will be 

 lost. Should it be found that too much water is lost, a very simple, 

 cheap and effective remedy will be, to cover the surface of the block 

 gutters with a light layer of tar concrete. This will make a gutter 

 that will be impervious to water, and thus equally as effective as brick 

 gutters. 



Several additional experiments on tar concrete drives have been 

 made. The specimen of drive laid by the Scrimshaw Patent Concrete 

 Company, in the fall of 1867, has steadily improved since its construc- 

 tion. During the year it has had no repairs, and no expense has been 

 put upon it except to sweep off the dust and mud brought on it by 

 carriages from the adjacent gravel roads. It is at the present time in 

 perfect order. From experiments which I have made, I have been con- 

 vinced that there is no difficulty to be anticipated in making repairs 

 either from the breaking up or wearing out of the concrete material. 

 If, from the unequal settlement of the ground, or any other causes, the 

 concrete should crack, a section of it can be removed and new material 

 put in its place, without material injury to the Drive surface ; and 

 when the surface has worn uneven, as it will in time, by constant use, a 

 new surface can be laid upon the old, and the adhesion is so complete 

 that no tendency to crack is exhibited. 



Samples of the Scharf Patent Concrete Pavement have been laid. 

 This promises well, and if it Avithstands the action of the frosts, it will 

 also make a jjood road surface. 



