48 
The method of procedure was to strip the top soil, partially 
improved in so far as the soil improvement scheme was com- 
pleted, and then raise or lower the grade as the need might be, 
afterwards replacing the top soil in order to have it ready for 
the completion of the soil improvement scheme, which followed 
directly the cutting and grading operations. In this way more 
than 4,500 cubic yards of subsoil were moved with a minimum 
of expense and a maximum of economic utilization of excavated 
material. Throughout the job we were digging the brook and 
making necessary changes in grade practically at the same time. 
Considerably more material was taken from the brook than was 
needed for raising the grade in the meadow and this surplus 
material was used as fill near the building. 
Nearly all of the bed of the brook is lined with clay, to 
prevent seepage into the surrounding area, but some parts of it 
were practically tight from the start. Several drainage and 
water pipes were crossed along the brook course, needing ad- 
justment, and these necessary changes have been made, with an 
indication of such changes on the irrigation map of the Garden. 
In one or two cases the brook leaked into adjacent drainage 
pipes, but all such evils have been corrected, we hope perma- 
nently, by completely encasing the pipes in concrete jackets, and 
by other methods. 
There are 19 changes of water-level in the brook, marked 
by dams or rapids. These have been made with glacial boulders, 
secured through the courtesy of Castle Brothers from an ex- 
cavation for a street they were constructing near the Garden. 
Most of these stones, several hundred in number, were hauled 
and placed by our own force. Nine large boulders, too heavy 
to handle with our own equipment, were hauled and placed by 
Harden Brothers, contractors. ‘The construction of these dams 
was difficult in that an appearance of artificiality must, if possible, 
be avoided. The Garden received much help in this work from 
Mr. Frederick Law Olmsted and Mr. Harold A. Caparn. On 
May 12, I went to Brookline to study with Mr. Olmsted some 
natural and artificial dams in the public parks there and in the 
Blue Hills reservation. Many changes in the details of both 
dams and rapids will undoubtedly be found desirable from time 
