FISHERIES, GAME AND FORESTS. 405 



FOUNDATION AND MASONRY. 



The surface rock in the river bed and on the west bank was quite seamy and 

 disintegrated and was, therefore, removed by blasting until solid rock was reached. 

 This was usually at a depth from three to six feet below the surface. The rock thus 

 found was remarkably free from any but fine closed seams and made an ideal founda- 

 tion for the dam. A few small springs were found under the main wall, but were 

 easily taken care of by building masonry wells around them in the following manner: 

 About a foot or two in height was built at a time, so that as the well filled with water 

 the pressure would not be sufficient to wash out the freshly laid mortar from the walls 

 of the well. Successive courses of masonry were built up as the preceding courses 

 became set, until the water from the spring had reached the level at which it would 

 flow no more. The water was then bailed out and the well filled with rich concrete. 

 The height to which the wells had to be built did not exceed four or five feet. 

 Before laying any masonry great care was taken to remove all the rock which had 

 been loosened by blasting and then to thoroughly clean the freshly exposed surface 

 with a hose and brooms. The surface left by the removal of the loose rock was quite 

 irregular, but to further insure against water following the foundation a layer of three 

 or four inches of two to one mortar was spread over the foundation, and the first 

 course of masonry bedded in it. The rock excavated from the bywash channel and 

 from the foundation, while solid, was found to break quite irregularly and could not 

 therefore be used for the facing of the dam, though entirely suitable for backing. 

 The facing was composed of large sized stone obtained from two quarries which were 

 opened up within about 500 feet of the east end of the dam. The stone^a syenitic 

 granite — is of a pink color, fine grained and extremely durable, as was shown by the 

 weathered outcrops of the quarry. It was found to be easily quarried into blocks, 

 ready, with little or no work on them, to be laid into the dam. Considerable latitude 

 was allowed in the joints of the facing, from one and one-quarter to one and one-half 

 inch joints being about the average obtained. The backing consisted of large 

 irregular stones laid in full mortar beds about a foot apart, with the intermediate spaces 

 filled with concrete thoroughly rammed to place. Stones of different sizes were 

 purposely laid adjacent to each other, so as to avoid any regular coursing of the 

 backing. The use of concrete in the above manner had the effect of considerably 

 reducing the quantity of cement which would be required had the masonry been laid 

 up in the ordinary manner by masons. No account was kept of the amount of cement 

 used in pointing with two to one mortar, but an average of the whole work gives 

 about twenty-seven per cent, mortar. 



