18 B. Silliman on the Deep Placers of 
This amount divided by eight and one-third millions, the daily 
supply, equals one hundred and fifty days’, or five months’ stor- 
age supp artial deficiency exists during three months of 
the year, from the middle of January to the “middle of April, 
during a part of which period, however, the demands for wash- 
ing are ata minimum. In ordinary years the reservoirs are not 
drawn from before the middle of August. In 1864, however, — 
ry 
e draft commenced as early as July Ist, owing to the ve 
exceptional dryness of that season. 
h 
e main canal after leaving Cafion Creek takes a westerly ' 
direction, and follows the contour of the hills on the south side _ 
until it crosses Jackson Creek, a distance of about seven miles; 
thence taking a more northerly direction for two miles, it crosses 
a depression in the ridge, and keeping above Weaver's or Hu- — 
reka Lake, follows the north slope of the ridge to Kureka, a dis- 
tance of about eleven miles; continuing in the same direction 
two miles further, it erosses a low depression by means of the 
ar 
Magenta and National aqueducts. Sieg: this it still follows the 
regi ravines. Often these aewheea are see sacs in- 
across 
secure, but the Magenta and National (or Washington) aque- 
ducts on the line of the Eureka Canal are remarkable exceptions 
to this. ‘They are thus described by Mr. Black 
“The an nta and a. ba bray which reflect “eee 8 on 
in carrying on the works of the Soe Nevada Lake oe Canal, on — 
the opposite side of the Yuba. The National nae ueduct is in length — 
1,800 feet; its greatest height sixty-five feet. The ta Aqueduct is 
q 
- 400 feet i in length, and its greatest height one hundred and pee : 
eet. 
The size of the flume is seven feet by one foot and three inches ; 
the inclination, or grade, one foot per hundred feet. The sides were 
made as low as practicable, so that the high winds which swee 
. 
any part of them; they are whole from foundation to top. The sides of 
the flume, one foot three inches j in depth, are formed of whole les 
are placed — 
thirty — in length and seven inches in width. The trestles 
thirty feet apart from centers; they are well and securely braced. The 
eee 
on actica p across — 
this gap might have little effect upon them. The posts of the trestles — 
were all hewn from trees growing in the vicinity, no splicing existing in 
