338 KANSAS CITY REVIEW OF SCIENCE. 
The reasons by which these proposals are supported seem so sound, that it is 
to be hoped that our government will soon take steps to test the efficacy of the 
proposed methods upon an adequate scale. 
The first of what is likely to ‘prove a series of works to control the low water 
discharge of our rivers is being built upon the Ohio River at Davis’ Island dam, 
five miles below Pittsburg. It seems a movable dam, of which you will find a 
brief description in Scrzbner’s Monthly Magazine for this month (May, 1880). 
The French have preceded us in works for regulating the flow of their navi- 
gable rivers, and have designed a number of types of movable dams (which they 
call ‘‘barrages”), which are well worthy of study and possibly of imitation. 
We shall doubtless make some changes, and perhaps improvements in them, to 
adapt them to our necessities and to our constructive methods; and this class of 
works should hereafter attract the study and attention of the members of profes- 
sion more than has been the case hitherto. 
The boldest and most interesting harbor work now being carried on by our 
government is probably the removal of the rocky obstructions in the East River 
of New York, at Hell Gate. 
General Newton, as you know, sunk a shaft in the rock at Hallett’s Point to 
a depth of some 50 feet below low water, honeycombed the rock with 7 426 linea, 
feet of galleries in various directions, and charging 4 427 drill holes in the re- 
maining pillars and roof with 49 915 pounds of ‘‘rend rock,” ‘‘vulcan powder,” 
and ‘‘dynamite,” blew up the whole Point, extending over three acres, and con- 
taining 63 135 cubic yards of rock, on the 24th of September, 1876. So accu- 
rately were the explosives located and proportioned, by the mathematical form- 
ulz worked out for the occasion, that not the slightest damage was done to the 
surrounding houses and premises. ‘The debris has since been removed with a 
grapple to a depth of 26 feet below low water. 
General Newton is now engaged in undermining in a similar manner the 
rocky island of eight acres (mostly under water) known as ‘‘ Flood Rock,” in the 
same vicinity. He has sunk a shaft, and driven, to May 1, 1880, 5 273 lineal 
feet of galleries, from which he has removed 19 044 cubic yards of rock, leaving 
a roof varying from 8 to 19 feet in thickness between the top of the galleries and 
the water in the tide way, which is from 6 to 12 feet deep. The holes are ail 
bored by machine drills driven by compressed air. 
(To be continued). 
SHIPS ON WHEELS. 
CAPTAIN JAMES B. EADS. 
A special meeting of the Chamber of Commerce was held at San Francisco 
recently, to allow Capt. James B. Eads, the famous engineer, to present his views 
on the subject of a ship railway, instead of a canal, across the Isthmus. After 
