Portland

3795

Port Louis

the leading wheat ports of the United States.

The population of Portland is 305,394- It
was 821 in 1850, 8,293 in 1870, 46,385 in 1890,
207,214 in 1910. Since 1912 Portland has been
governed by a board of five commissioners
(one acting as mayor), elected by popular
vote for four years on an alternating basis.
Portland was founded in 1845 by A. L. Love-
joy and T. W. Pettygrove, New England real
estate men, who named it after Portland, Me.
It was chartered as a city in 1851. The Lewis
and Clark Centennial Exposition was held
here in 1905.

Portland Canal, an inlet of British Co-
lumbia which stretches from Dixon Entrance

hydraulic cement was developed between 1756
and 1824. Portland cement is a fine powder
of dark gray to greenish color, weighing about
90-100 Ibs. per cubic foot (packed in bags of
94 Ibs.), and of specific gravity (weighed in
oil) from 2.9 to 3.2. It does not deteriorate
by storage, if kept dry. Mixed with about
25 to 30 per cent, of water, it forms a smooth
paste which by mixing with one to three
times its bulk of sand becomes cement mortar.
Mortar mixed with two to three times its bulk
of gravel or broken stone becomes concrete,
by far the most important use of Portland
cement. In final consistency, mortar or con-
crete is like a hard limestone or trap, and in

Portland, Oregon: The Gorge of the Columbia as seen from the Columbia River Highway.

of Hecate 'Strait in a northwesterly direction
for about 80 m.., and which opens into the
Pacific at lat. 55° 25' N. The Alaskan boun-
dary arbitrators decreed in 1903 that the
boundary line should run from Cape Mur-
zon, the southern extremity of Prince of
Wales Island, up Portland Canal, leaving the
islands Wales and Pearse within the British
limits.

Portland Cement, one of the general
class of cements second only to steel in im-
portance as an engineering material, is an ar-
tificial product similar to natural (Roman,
Rosendale) cements, but superior to them in
strength. Portland cement is produced by
mixing finely pulverized limestone (or chalk
or marl) and clay (or shale), in proportions
of about 75 to 25; grinding them together;
then burning (clinkering) the mixture at very
high heat; and lastly, grinding the resulting
slag (clinker) to an impalpable powder. The
<act that such a process produces a valuable

both tensile and crushing strength it is equal
to good specimens of best stone. In this stone-
forming powder lies the entire value of Port-
land cement. In American manufacture, the
cement is burned in rotary kilns, which are
horizontal, slightly inclined steel cylinders 6
ft. in diameter, 60 to 150 ft. long, lined with
refractories, rotated by power, having a flame
fed by pulverized coal blown in at the lower
end, and the cement mixture fed in at the
other or chimney end. This machine has a
large capacity, and is economical of labor
and fuel. The largest amount of Portland ce-
ment is made in the United States. Eastern
Pennsylvania was the original center of man-
ufacture, and is still the largest producer; but
cement plants now exist in nearly every State,
See CEMENT; CONCRETE.

Port Louis, the capital and principal port
of the British colony of Mauritius, is situated
on an excellent harbor on the n.w. coast. It
is defended by forts; is a coalins; station of