298 
OBITUARY NOTICES. 
that are yet uncovered, although careful investigators are 
delving into the mysteries of the ocean bottom with the hope 
of finding them. The late Professor Hilgard believed the 
mud holes off the approaches to New York were connected, 
as was subsequently proved. I recall discussions with him 
about them, and doubt not they had been a topic between 
him and Mr. Lindenkohl before the survey that demon¬ 
strated the deep canon and which Mr. Lindenkohl seized 
upon to strengthen his theories on the Hudson River 
bottom. His researches in oceanograph}^, always a subject 
of study by him, were finally promulgated in his paper on 
the Specific gravity of the waters of the Gulf of Mexico and 
the Gulf Stream, and in a paper on the Gulf Stream, pub¬ 
lished shortly afterwards in Petermann’s, he enlarged upon 
the suggestions conveyed in the former paper that, in the 
physical conditions of the ocean, the different densities and 
temperatures of the water at different depths would tend to 
produce that great ocean current, in a manner, if not con¬ 
vincing, at least worthy of his pen and the years he had 
given to the compilation of facts and study of the subject. 
He was rewarded in the Coast Survey by rapid promotion 
through all the grades of his profession until he became a 
recognized authority on chart publication. Being endowed 
with a remarkable memory for facts and dates, his intimate 
acquaintance with the chart work of the Survey during his 
fifty years of service was of great value in all matters con¬ 
cerning the compilation of charts from the older records. 
The numerous drawings compiled and made by him bear 
witness to the skill and fidelity which distinguished his 
career. His work was always rapidly executed and charac¬ 
terized by accuracy. 
During the Civil War, in 1862-1864, he was detailed to serve 
with the army as topographer, thus aiding in the preserva¬ 
tion of the Union. His first service was in aiding Assistant 
A. M. Harrison in the topographic survey of the northern 
bank of the Potomac River in the vicinity of Rosiers Bluff; 
in December, 1862, under the direction of the Engineer De- 
