Blasting of Rocks—Dangers and Remedies. 135 
powder would be therefore, particularly liable to be thrown up around 
the spindle. By proceeding with the tamping, this powder would be 
brought in close and hard contact with the spindle, and in withdraw- 
ing the spindle in the manner mentioned by Mr. Catlin, would be 
subjected to violent attrition, between the spindle and the gypsum or 
between the spindle and the rock. Whether this was or was not the 
precise cause of the explosion, cannot perhaps be determined ; nor 
will it be important to know, if, without this knowledge, satisfactory 
information can be given in regard to the manner in which the recur- 
rence of similar accidents may be prevented in future. 
About twenty years since another method of charging a blast was 
proposed and circulated in the newspapers, which, since that time, has 
been practised to some extent in different parts of this country. ‘This 
method may be briefly described as follows, viz. After putting in 
the powder, take arye or wheat straw, which is long enough to reach 
from the powder to the top of the hole, and haying filled it with 
powder, insert one end of it into the charge; after which put in a 
small quantity of wadding, and then fill up the hole with coarse dry 
sand, simply poured in without any ramming. 
When about ten years since my attention was turned to blasting, 1 
made a trial of this method, with great success in some cases but 
without any effect in others. I soon found that when the hole was 
deep, the effect was not only certain, but also more powerful than 
when charged in the old method. But when the hole was shallow, _ 
the sand would generally be thrown out without producing any effect 
on the rock. When the depth of the sand above the powder is not 
less than ten times its diameter, I have never known it to be thrown 
out. In all such cases therefore, I can from experience recommend 
this method as one which is perfectly safe and sure, and at the same 
time more expeditious and more effectual than the old method. 
Since my attention has been drawn to this subject by Mr. Catlin’s 
letter, an equally safe method has occurred to me, of securing a blast 
in holes of jess depth. ‘This method is as follows; viz. Having put 
in the powder, and inserted into it, on one side, the straw filled with 
powder, as directed above, put in a small quantity of wadding and 
press it compactly down; then make a cone of wood, the diameter 
of whose base is a little less than the smallest diameter of the hole, 
and whose height is a little less than the distance from the top of the 
wad to the top of the hole. Set the base of this cone on the wad, 
and then keeping the vertex in the centre of the hole, fill in around 
