Prof. Treadwell's Improvements in Cannon. 99 
Parrott and others. Whatever may be the relative merits of 
these several varieties, our interest is confined to the question of 
steps, and the only steps, which give distinctive character to the 
guns under consideration. Both originated with Mr. Treadwell. 
These two inventions are often confounded, although more 
than ten years elapsed between them. The confusion is doubt- 
less Owing in some degree to the fact that the two are found 
combined in nearly all the modern built-up guns. e first 
Initiated a system of construction which may be designated as 
the coil system ; the second, what may be named the hoop system. 
The first was successfully applied to the making of cannon by 
Mr. Treadwell in the yedr 1842, and a full account of it was pub- 
lished in 1845; the gist of the invention being in so construct- 
ing the gun that the fibres of the material shall be directed 
around the axis of the calibre. 
This method of construction is described in Prof. Treadwell’s 
Own language as follows: ‘Between the years 1841 and 1845 
T made upwards of twenty cannon of this material [wrought 
‘ron]. They were all made up of rings, or short hollow cylin- 
ders, welded together endwise; each ring was made of bars 
wound upon an arbor spirally, like winding a ribbon upon a 
block, and, being welded, and shaped in dies, were joined endwise 
when in the furnace at a welding heat, and afterwards pressed 
together in a mould by a hydrostatic press of 1000 tons’ force. 
Finding in the early stage of the manufacture that the softness 
of the wrought iron was a serious defect, I formed those made 
afterwards with a lining of steel, the wrought iron bars being 
Wound upon a previously formed steel ring. Hight of these 
Suns were 6-pounders of the common United States bronze pat- 
tern, and eleven were 32-pounders of about 80 inches’ length of 
and 1900 pounds’ weight.” ans te 
The soundness and value of this principle of construction 
Were fully confirmed in England by the experiments of Sir Wil- 
liam Armstrong in 1855, and attested by his —— before a 
"Tibes his own gun as one “ with a steel tube surroun 
Coiled cylinders,”—as “peculiar in being mainly com 
tubes, or pipes, or eplidae rs, formed by coiling spirally lo 
of iron into tubes and welding them on the edges, as is 
t-barrels.” His indirect testimony to the originality of Mr. 
'Well’s process is equally clear; viz: that, within his. 
edge, no cannon had ever been made upon tl 
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