USE OF REND-ROCK. 39 



With me the lifting apparatus has not proved a profitable 

 investment ; while with m}' next neighbor it has worked Avell. 

 After various experiments I have found it more profitable to 

 let out the uncovering and drilling as piece-work, paying a 

 price per inch for drilling, which includes uncovering also, 

 when the bowlders need blasting ; otherwise, then a special 

 price for uncovering. 



At the present time I pay six cents an inch, find powder 

 and drills, and pay for the sharpening of the same. I have 

 no doubt but that to many this reads like very good wages ; 

 and some shrewd Yankee who is reading this is itching to 

 get liis pen and ink, and offer better rate, with the idea that 

 there is money in it. By the old-time way of blasting there 

 would be very good wages to be made at these rates ; but 

 there has been a change in the character of explosives, and 

 of these I have availed myself. My bowlders are of all sizes, 

 up to twenty tons to a single stone ; but those we blast aver- 

 age about four tons' weight. The average depth of the holes 

 drilled was at the start about ten inches ; but, with increased 

 experience and improved explosives, the depth has been de- 

 creased to the average of about five inches, while the diame- 

 ter of the holes has at the same time been much lessened. 

 The explosive I now use is rend-rock, — an admixture of gun- 

 powder, while in a pasty state, with nitro-glycerine. This 

 powerful explosive, though well known and very generally 

 in use by contractors on public works, is yet so little known 

 by farmers in general, that I think it will be worth while for 

 me to give them an introduction to it, as its use enters so 

 largely into the economy of handling bowlders. 



Rend-rock is sold (I get mine of George H. Sampson, 25 

 Congress Street, Boston) in paper cartridges of various 

 sizes, at the rate of fifty cents for lots under fifty pounds. 

 It is fired with powerful caps, wliich cost two cents each. 

 The material is generally used by tearing open the cartridge, 

 and taking as needed. As will be seen, it is over twice as 

 costly as common blasting-powder ; but, • as every farmer 

 knows, the great cost in blasting is the drilling, and this is 

 where the saving comes, as it will do as much execution as 

 gunpowder in a hole of one-third the capacity. Again : it 

 can be loaded far more readily ; push it down hard with a 

 stick, and, inserting the cap, fill up with any coarse soil at 



