. The Bell System technical journal . Fig. 21—Removing Granite Blocks and Breaking Concrete Base USE OF LABOR-SAVING APPARATUS 73 Where trenching work involves cutting through paved streets onecompressor unit with three men will ordinarily accomplish as much in agiven 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 mangoes ahead and wedges the blocks loose, while the man followingbreaks the concrete base. Some pavements of this type are verydifficult to open. When the
. The Bell System technical journal . Fig. 21—Removing Granite Blocks and Breaking Concrete Base USE OF LABOR-SAVING APPARATUS 73 Where trenching work involves cutting through paved streets onecompressor unit with three men will ordinarily accomplish as much in agiven 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 mangoes ahead and wedges the blocks loose, while the man followingbreaks the concrete base. Some pavements of this type are verydifficult to open. When the cement filling is of good quality thegranite blocks often break before the cement Fig. 22—Air Gun Cutting Asphalt Fig. 22 shows an operator cutting asphalt pavement. With thewedge-shaped blade cutting at intervals as shown, small cracks areopened between the holes so that when cross cuts are made squareblocks of asphalt can be readily lifted out. The above illustrations contrast rather strikingly with the oldmethods of cutting pavements by means of sledges and bars as shownin Figs. 23 and 24. In the use of the old manual method of cutting with sledges and barsthere is always present a certain degree of hazard to the men. Thereis the possibility of the striker missing the steel and striking theholders wrist, also the danger to the mens eyes from flying steelchips. These safety points, of course, are outside the labor savingconsiderations. 74 BELL SYSTEM TECHNICAL JOURNAL
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