Mathematical and Physical Papers. 247 



or cutting out in any way. The water flow immediately picked up 

 to 50,000 gallons per day, and held to this for a long period. We 

 were draining out the entire basin under the hill, for such it proved 

 to be. The springs commenced to fail, the wells to fall in their 

 water-levels ; the dam was broken. 



■ "The putty clay in heading lasted for nearly 100 feet and was 

 very hard to manage, a special tool being made to cut it — a compro- 

 mise between a mattock and the chisel point of a pick. Picks only 

 went into it and drew out their width in clay. Mattocks could not 

 be driven in deep enough to avail anything. After passing through 

 this material a solid sand bed was encountered that required very 

 careful handling to prevent its falling away from the putty clay, 

 which had risen beyond the roof. This condition lasted, to the end, 

 a distance of 279 feet. Careful record had been kept of channels 

 and slight depressions in the blue-clay level as the tunnel was 

 driven. Each depression was marked in the timber sets. At the 

 end wo found a depression of four feet and six inches, and con- 

 cluded that it was best to stop at this point. The drain had af- 

 fected the old-tomb spring, one of our guides, reducing it by 

 one-third ; still with the clay depression at the end of the tunnel it 

 seemed to be safer and cheaper (due to long haul ) to cut No. 2 

 tunnel to isolate old tomb. It was necessary now to take up the 

 depressions indicated in tunnel No. 1. A ditch with a grade of two 

 inches to the 100 feet was started under tunnel No. 1, to take up 

 the lowest depression, four feet six inches at its head. This tun- 

 nel had been timbered with a view to this. The timbers had been 

 set four feet apart at the bottom and two feet at the top, so that a 

 stringer could be run from No. 1 timber on the bottom to No. 3 on 

 each side of the tunnel, and a jack placed across No. 2 timbers. 

 This was tightened up and No. 2 mudsill taken out, thus swinging 

 No. 2 so that the ditch could be cut out between these sets. This 

 ditch was cut and the depression thus all taken up. The deepest 

 depression had clay cores rammed down on the outflow side of the 

 tunnel. This ditch was then filled, first with three inches of clear 

 gravel from the size of a walnut to the size of a pea, thoroughly 

 rammed. On this were laid three two-inch tile-drain pipes in pyra- 

 mid form. The entire ditch was then filled in with the same gravel. 



The flow of water was 10,500 gallons per day. The springs and 

 weeps as far as old tomb were practically dry. The well at the 

 house, 150 feet distant from the tunnel, was dry. The greenhouse 



