Steam Engine. 85 
then to keep these segments in constant tendency tb the 
place of action, there are a set of springs very nicely com 
trived to act on the concave edge, which, no doubt, will 
keep them to their work ; but the difficulty is how to pre- 
serve the fit at the junctures : it is impossible for the seg- 
ment of a small circle to become the segment of a larger 
circle^. But we do not suppose Mr. Cartwright to have 
intended this metallic packing to compensate the irregu- 
lar figure of the steam-vessel, for it is impossible ; beside, 
Mr. Cartwright’s notions of accuracy would never suffer 
him to admit a steam-vessel to his engine which was not 
a perfect cylinder ; in which case these segments may have 
but little wear, though, if they were of metal in any degree 
softer than the cylinder, the dust which will find its way 
there, would wear away the cylinder so as to be sen- 
sibly detrimental : added, that this packing could never 
apply to a double engine. It, however, serves as a very 
elegant specimen of the inventor’s inclination to accurate 
working. 
Since the above was written, we have seen an engine of 
Mr. Cartwright’s at a tan-yard near Horsley-Down,f 
wffiich gives great satisfaction to the proprietor. The piston, 
by the account of the tender of the engine, has not even been 
looked at for many months, nor has he any indications 
that it will be necessary for many more. This account 
receives strong confirmation by the appearance of the 
quantity of condensed steam which is discharged from the 
engine every stroke, which, as it is not effected in the com- 
mon way (by injection), can be very exactly estimated. 
* Admitting that these segments wear away on the outer arch‘d 
es, the inner arches must recede from the centre, and therefore wifi 
fee one continued deduction from the entire circle, 
t Near London. 
