AMERICAN RAlLR0A1),.,..rIL°URNAL-

v6 83

to the limited weights passing under them; but this
ﬂexibility would be inadmissible in a railway
bridge, and the continuity of the rail would be de-
stroyed if a very small deﬂexion took place when
passed over by a heavy locomotive. With a view
to give this necessary rigidity, Mr. Brunel has in-
troduced at every third part of the tube a stiff
wrought iron girder, connecting firmly the tube to
the roadway girders; and, with the aid of ad-
justing screws, the suspension chains are pulled or
stretched as nearly straightas desirable. Other
diagonal chains connect these points, so that at
whatever part of the bridge an engine may be pass-
ing its weight is distributed all over the tube and
chains by these arrangements.

The tube is laid upon the iron standards, but is
free to move upon rollers at the top of the masonry
standard. The expansion on the hottest day yet
experienced has not exceeded one inch.

The tube is strengthened within by the introduc-
tion ofdiaphragms or discs at every 30_.feet, which
renders it both light and stiﬁ‘.

The roadway girders are formed of a deep thin
plate of iron stiifencd at intervals at the top, it has
a strong triangular cell to resist compression, and
at the bottom a double plate of rivetted iron to re-
sist extension. Small cross girders are rivettcd to
these side girders diagonally. On these 4 inch
crcosoted planks are fastened crossing them in the
opposite diagonal direction. Eighteen inches of
gravel are laid over this ﬂoor, and on this bed the
ordinary permanent way on longitudinal sleepers.
One roadway was opened for travel on the 19th of
July last, the tube and other portions of the second
part are ready to be put up.

Annexed is a summary of the cast and wrought
iron used in the bridge 3--

Tons. cwts. qrs.
Wrought iron, in three spans of 100
feet each, double line . . .. . . .. . . 277 0 0
Wftluglll iron in the girders, ﬂoor-
bearers, and other work of the

 
 

main span of 300 feet, double line 278 6 1
Two wrought iron tubes, each 312
feetlon . . . . . . . . . . . .  302 1] 0
Wrought iron beam on the standard
to support the tubes . . . . . . . . . . . . 5 0
Vertical trusses . . .. . . .. . . . . . . . . . 3'7 0 1
Tie girders to connect the caps of
co111mns.... . . . . . . . .  10 0
Suspending links in main chains
and diagona1s.... .. . . . . ..  256 5 2
Saddles at points of suspension roll-
ers.... . . . . . . . . . . . . . .  41 10 1
Adjusting screws . . . . . . .. .  .. .. 2 10 0
Rollers of main tube . . . . . . . . . . . . . '7 1'7 3
Rollers of girders . . . . . . . . . . . . . . .. 2 11 3
Bolts........................... 3 15 0
Total wrought iron.. .. .. .. ..1231 2 2
. 1 , Tons. cwts. qrs.
Cast-iron bed plates for trusses . . . . . 24 6 1
“ standard.... .. .. 128 6 O
“ caps for columns and par-
apets....‘......,....i... 0
“ cylinders in the support-
ingpiers.............. 830 0
Total cast iron,.». . . . . . . . . . . . . 1003 12 1
3?.-ii’l‘£‘..’§f. T’f‘?’.‘II:2 33% 13 i } 2934 14 4

Masonry in abutment and pier, 3240 cubic yards.

Total estimated cost of the bridge when entirely
completed, £65,420.

A number or ingenious arrangements are con-
nected with the bridge to ensure elements of strength
and rigidity in the structure. Among these may
be mentioned the cast iron ring or circle attached
to the ends oi the tube to prevent collapse; to the
wedges introduced under the vertical trusses to ad-

just the exact tension upon the-‘cha"ih’;Tt‘0'£li‘e curve?
given to the tubes themselves, increasing their
strength; and to the roller-boxes under the vertir-.al3
trusses, by which means the road girders are main?
tained in a position to expand or contract independ-
ently of the movements of the main tube. A

The Mountain Lake Water Company of
San F1-itnclsco.

New York and Boston boast the engineering
skill and costly works that have supplied them with
that most important acquisition for city salubrity,
pure water; and San Francisco Will, we hope, soon;
be able to point to the abundant streams derived from
her mountain springs and lakes. indeed we may
entertain the hope that this will be a precursor to,
other works of internal improvement in our El Do-
rado State, and that the valley of the Sacramento,
and San Joaquin may be traversed by railroads.
even before California is connected with the two;
iron arms that now are reaching forth to bind her,
on the one hand with the Gulf of Mexico, and on
the other hand with the Great Lakes and the St.
Lawrence.

The Mountain Lake company was organized on
the l4th'August, 1851, under the general corpora-
tion act of California, and a grant ol"the city of
San Francisco to lay down pipes in the streets ol
that city for 530 years, and an exclusive privilege
for the term of 5 years from the 1st January, 1853,
on condition that the corporate authorities of San
Francisco shall use the water Ior extinguishing
fires and also that after the‘ completion of the
works, the supply shall not fall below one million
of gallons daily.

We learn lrorn the report of the Engineer, Henry
S. Dexter, Esq., that the Lake is on the line of Pa-
ciﬁc St. San Francisco, produced, and 3 miles and
2'25 rods distant from the corner of that street and
Kearney street. On the 1st of‘Dece'mber, after two
dry seasons, the surface of the lake’ was 123 '76-100
feet above Paciﬁc wharf, and its area '72; acres.-«-
The average depthwas 16. When full, the Lake
has an available depth of 24 i'eet,”,and an area of
10; acres. It is situated in a basin surrounded by
hills, some rising 300 feet above ‘it, and receives
the drainage of a considerableextent of country.-,
There is no visible outlet, thcrebcing about 300
yards from the head oi the ravine through which
the brook ﬂows, which discharges the percollating,
waters of the lake. ' This ravine is} of a mile

' long, and has an average width of 100 yards. The

hills skirting it are higher than tl1e,Lake, and the
ridge separating the lake from the ravine is 18 feet;
above the surface of the lake. Of course to render
the water available for the supplyot‘ the city, it is
necessary to intercept the ﬂow of the water through
the ravine, it is proposed to effect this by running
a puddle wall and ditch across the ravine, and car-

ry it as high as the surface of the water. The wall ,

is to be carried down to the hard pan orother strata
impervious to water, and in its centre a row of sheet
piling composed of 3 inch red wood planks sawed
for the purpose and battened with inch red wood
boards is to be inserted. At the lake two powerful
steam engines are to be erected, forcing the water

from the lake to a ‘distributing reservoir on Cannon
Hill, in the neighborhood of the city. The pipe
connecting this reservoir and the pumps is to be 16
inch bore. 1.} inches thick for the first 9,100 feet,

and decreasing in thickness towards the summit.——-
The bottom of the reservoir on Cannon Hill will
be 360 feet above Paciﬁc wharf, and 236 above the
lake surface, the distance of Cannon lHill”fr'om

‘*1‘

the lake is about 1;, miles, and 2; miles from the

"corner of Paciﬁc {and Kearney streets. The cost of

pipes, engines, reservoirs, etc., by this plan, is es-
timated at $459,453. Another plan dispenses with
pumps, and conducts the water from the lake to a
distributing reservoir, at a level of 107 feet above

f Paciﬁc wharf, on the slope of a hill at the North
' Beach. The estimated cost of this line is $392,971.

The estimated gross income for the year 1852, is
set down at $10 a month, for 3,000 houses $360,000,
and for 1853, for 5,000 houses $600,000.

The lake forms a species of natural reservoir,
and is fed by springs—-the main body of its waters
are supplied by the lower strata passing through
the adjoining hills, and extendingto the high range
on the opposite side of the entrance to the harbor.-—
The present outlet forms a rapid brook, the dis-
charge of which is estimated at from 8 to 10 million
gallons daily. A similar lake in the vicinity called
the Lagmta H09Ld(b and 200 feet above the Moun-
tain lake, can be added to it in case the supply is
not suflicient. This, it is estimated, will furnishtt
to_5, million of gallons daily. V _ t

Thus at an expenditure of less than $500,000 the

city of San Francisco will be supplied with pure
and wholesome water. An almost equally import-
ant considcration is the protection of the city, and
the mcrchandizc of which it is the depot from de-
struction by tire. The numerous destructive con-
flagrations that have swept over that city destroying
millions of property, show the necessity of an abun-
dant supply of water. Its’ exposure to strong winds
springing up daily, has hitherto rendered the most
solidly constructed stores and warehouses insecure,
and it is only by the introduction of -uniailingland
copious streams of water that exemption can be
hoped for. The works which are destined to secure
this end must prove as proﬁtable as they are indis-
pensable to that capital of the gold region, and pro-
bable centre oi the tuture mighty commerce of the
Paciﬁc basin.

 

Mississippi and Chicago Railroad. ,

We learn, says the Chicago Tribune, that the
party of Engineers, appointed to survey a line tor
the Mississippi and Chicago railroad, have reach-
ed the Sumrnit,—about twelve miles from the city,
ontheir way to this point. We are informed that
the surveys show a much more favorable grade
than was expected. The survey is through Lock-
port, to touch which requires scarcely any diverg-
ence iroma direct line.

It is rumored that the parties interested are try-
ing to make arrangements for the sale of that por-
tion of the Rock Island and Chicago road, lying
between this city and Juliet, to the Mississippi and
Chicago company, and that the lattcrdwill, next
year, construct a mat of track irom Jolict to La.
Porte. 

me
an ,-

. l ‘L V . V -in k I .. ‘J! 
I-Ioole, Sta.n1forth~ & '00.,
MlNERVA WORKS, .
SI-IEFFIFLD,

Steel Converters and Iteﬁnere; ‘.11

Manufacturers of Improved Cast Steel Engineer-
ingand Machine Files; ,
5 ocornotive Engine, Railway Carriage and Wagon
‘pin 8. ., _ .. ..  _, .

guvvgs of every description, Engineers, Hammers,
etc., etc., etc. i p ,

An assortmentef Steel from the above Works con-
stantly on ‘hand by RICHARD’ MAKIN, ’

Agent for the Manufacturers,
43tf 65 Broad, strret.

Huger, '1‘. P. 1

Northeastern Railroad, Charleston, S. C.