ae 
340 | Reciprocating Magnetic Attraction. 
joic A late article on the subject which accords in its facts 
with other statements which I have, contains the following statements. 
“«'The whole number of steam boats which have been built upon 
the western waters is about three hundred seventy five. Some of 
them are of five hundred tons burden, and from that.down to one 
hundred, and their average not over two hundred tons. The num- 
ber now in commission is something over two hundred. Their an- 
nual expense for fuel is estimated at one million one hundred and 
eighty one thousand dollars, and the other expenses at one million 
five hundred thousand dollars. _. i 
_ “The value of steam navigation to the United States, and:partic- 
ularly to the great valley of Mississippi, is incalculable ;. it defies the 
power of calculation. We doubt whether the citizens of the United 
States, who duly appreciate its importance, would be willing to part 
with it for the amount of the debt of Great Britain of eight hundred 
millions of pounds sterling. But for the introduction of steam navi- 
gation into the United States, and its bringing, as it were into juxta 
position, the extreme regions of her widely extended borders by 
“ conquering time and space,” and but for its happy influence in pro- 
moting international commerce, and social intercourse by the ties of 
interests it creates, in a thousand different: ways, the Atlantic and 
Western states would soon have become alienated from each other, 
and a separation would have been the consequence.’ Ye 
- three hundred thousand, making an aggregate-of nearly two million - 
ae 
Art. XVIL—On a Reciprocating motion produced by Magnetic 
ss _ Attraction and Repulsion ; by Prof. Josepn Henry. 
TO THE EDITOR. : 
Sir,—I have lately succeeded in producing motion in a little ma- 
chine by a power, which, I believe, has never before been applied 
in mechanics—by magnetic attraction and repulsion. ! 
Not much importance, however, is attached to the invent 
the atricle, in its present state, can only be considered a philosoph- 
ical toy ; although, in the progress of discovery and invention, It 1S 
not impossible that the same principle, or some modification of it on 
a more extended scale, may hereafter be applied to some useful pur- 
ion, since 
pose. But without reference to its practical utility, and only viewed 
4 § 
2 sg 
