Dodge.] 
200 
[May 18, 
and solid slate was then blasted out. In the fall of 1879 a sewer 
was laid in Kennard Avenue. By the kindness of the gentlemen 
of the Sewer Department office I have been able to ascertain 
the particulars of the occurrence of the rock here, and have been 
furnished with a fragment of it. 
The ledge was uncovered for about 100 feet from Poplar Street, 
and the channel for the sewer was sunk three and one-half feet into 
the slate rock, which yielded to the pick without blasting. The 
direction of the sewer is north-east and south-west, and the ser- 
rated outline of the section is so like one along Lowell or Bel- 
mont Streets on the south side of Spring Hill in Somerville, with 
the low south-westerly dip alternating with the shorter slope 
across fractured edges of the strata, as to leave little doubt that 
the north-west — south-east strike prevalent in Somerville ex- 
tends to this place. The general original shape of the Barton’s 
Point neck, too, favors this view. For want of positive observa- 
tion to this effect, however, this cannot be definitely asserted as a 
fact at present. 
At Sears Building, corner of Washington and Court Streets, 
which stands 35 or 40 feet above city base, slate has been reached 
at a depth of 60 feet. It also occurs along Charles Street, at 18 
feet depth, that is, substantially at the base level, at the foot of 
Pinckney Street, at 27 feet, south of Mt. Vernon (surface height 
at corner of Charles and Mt. Vernon is 16.6), and at 31 feet, north 
of Chestnut (Charles and. Chestnut 16.4). At the corner of Brim- 
» 
mer and Mt. Vernon piles are driven without impediment to a 
depth of 40 feet. 
At the artesian well opposite the Providence Railroad station, 
on Providence Street (17 feet above city base), fragments of slate 
began to mix in the sandy clay at about 165 feet depth, at 200 
the drill was in solid slate as the washings of its chips showed. 
Below 1000 feet there appeared to be a good deal of decomposed 
pyrites in the slate, and after 1200 a considerable amount of visi- 
ble quartz. At 1440-1465, a harder quartzose rock was encoun- 
tered which reduced the progress to a foot and a half a day. 
Careful examination of the material washed from the shaft at 
1520 feet showed the presence of numerous green, acicular crys- 
