278 
end of the war and the date of his death on 
Aug. 8, 1882, would extend this notice beyond 
reasonable limits. They can only be classified 
and briefly explained. | 
As an expert in railroad-engineering, Gen. 
‘Warren served on three different commissions 
to inspect and report upon the construction of 
the Union Pacific and Central Pacific roads and 
their branches, and to indicate their proper 
point of junction. 
His military experience caused him to be 
selected to make the detailed surveys of the 
battle-field of Gettysburg, and of the vicinity 
of Groveton, Va., in connection with the Fitz- 
John Porter investigation. 
As an hydraulic engineer, his labors covered 
several of the most important works in the 
United States, and gave him great eminence. 
He was a member of the board to report upon 
the Fort St. Philip canal project, and was 
president of the commission of engineers ap- 
pointed by special act of Congress to report 
upon the best method of protecting the alluvial 
region of the Mississippi against overflow. 
He conducted a very elaborate survey and in- 
vestigation with a view to improve the naviga- 
tion of the Fox and Wisconsin rivers; and his 
report, a model of excellence, has borne the 
test of practical trial subsequently applied. 
His surveys and reports upon the improvement 
of the upper Mississippi and of the Minnesota 
River are also of standard authority. His 
name is identified with the improvement of the 
Connecticut River, and with various harbor im- 
provements upon the coast of Massachusetts, 
Rhode Island, and Connecticut ; and his labors 
in hydraulic engineering at other special locali- 
ties are too numerous to mention. 
Gen. Warren also contributed much to the 
subject of bridge-construction. The Rock Is- 
land bridge was built essentially upon his plans 
and specifications; and his services upon 
boards ordered to report upon bridges pro- 
jected or constructed at many important locali- 
ties involved great labor and research. His 
reputation in this branch of engineering, how- 
ever, will chiefly rest upon his monograph 
upon bridging the Mississippi River between 
St. Paul and St. Louis. This work was unique 
in character. The investigation was ordered 
by Congress to collect data for harmonizing 
the conflicting interests of navigation and of 
railroad transportation; and the subject was 
treated exhaustively, not only from an engi- 
neering, but also from a legal point of view. 
The investigations extended over a period of 
more than eleven years; and the report is a 
standard authority to be consulted in any 
SCIENCE. 
Py ea) eee 
ae” 
[Vou. III, No. 57. 
future bridge-projects over navigable western 
waters. 
Gen. Warren’s natural fondness for geologi- 
cal research has already been mentioned. His 
extensive explorations in Dakota and Nebraska ; 
his numerous surveys for determining the topo- 
graphical features of the valleys of many rivers 
in Minnesota, Wisconsin, Iowa, and Illinois ; 
his investigations in respect to foundations for 
bridges in this district ; and his thorough famil- 
larity with all the geological and topographical 
reports upon this vast region, and north of it 
in British America, — enabled him to frame an 
hypothesis as to geological changes that have 
occurred, and are now occurring there, which 
is both novel and brilliant. He first announced 
it in a paper read at the Chicago meeting of 
the American association for the advancement 
of science in 1868, and subsequently elaborated 
it in his report upon the Minnesota River and 
in that upon bridging the Mississippi. 
Very briefly outlined, it is the following. 
Lake Winnipeg formerly covered much more 
space than at present, and extended southward 
to the head of the Minnesota valley, through 
which it drained, thus forming the source of 
the Mississippi. ‘The present outlet to Hudson 
Bay (Nelson River) did not then exist. The 
change of drainage has been. effected by an 
elevation of the southern, and a subsidence of 
the northern, portions of the continent, which 
have been in slow progress for a vast period of 
time. When this change began, it caused a 
decreasing river-slope in the northern portions, 
and a diminishing power to erode. The resist- 
ance due to the granite ledges extending over 
a hundred miles below Big Stone Lake, in the 
bed of the upper Minnesota, checked further 
erosion there, and formed a growing lake above 
it, which finally found a new outlet to Hudson 
Bay through the loose drift near Nelson River. 
This was rapidly eroded, thus reducing the old 
lake-surface to the present level of Lake Win- 
nipeg, which is about three hundred and sixty 
feet below the present sources of Minnesota 
River. Like changes, due to the same cause, 
by which Lake Michigan has been cut off from 
the Illinois River, and Lake Winnebago from 
the Wisconsin River, may be traced. 
Gen. Warren discussed this hypothesis in 
detail, and showed, by so many facts as almost 
to amount to a demonstration, that, since the 
glacial epoch, two secular oscillations of this 
character have occurred in this region. The 
reasoning is masterly, and illustrates both his 
breadth of conception, and his care to conclude 
no farther than the facts warrant. 4 
Although modest and retiring to a fault, the 
