USE OF LABOR-SAVING APPARATUS 



73 



Where trenching work involves cutting through paved streets one 

 compressor unit with three men will ordinarily accomplish as much in a 

 given period of time as 27 men employing former methods. 



In Fig. 21 two operators are shown opening pavement which con- 

 sists of granite blocks set in cement, on a concrete base. One man 

 goes ahead and wedges the blocks loose, while the man following 

 breaks the concrete base. Some pavements of this type are very 

 difficult to open. When the cement filling is of good quality the 

 granite blocks often break before the cement loosens. 



Fig. 22 — Air Gun Cutting Asphalt 



Fig. 22 shows an operator cutting asphalt pavement. With the 

 wedge-shaped blade cutting at intervals as shown, small cracks are 

 opened between the holes so that when cross cuts are made square 

 blocks of asphalt can be readily lifted out. 



The above illustrations contrast rather strikingly with the old 

 methods of cutting pavements by means of sledges and bars as shown 

 in Figs. 23 and 24. 



In the use of the old manual method of cutting with sledges and bars 

 there is always present a certain degree of hazard to the men. There 

 is the possibility of the striker missing the steel and striking the 

 holder's wrist, also the danger to the men's eyes from flying steel 

 chips. These safety points, of course, are outside the labor saving 

 considerations. 



