224 Miscellaneous Intelligence. 
affords a much tougher material than when effected too rapidly. 
This annealing of cast iron, we believe, is frequently neglected, 
and we can speak from experience of its high importance. The 
best test of the quality of a piece of cast iron is to strike the 
edge with a hammer; if it make a slight impression, denoting 
some degree of malleability, the iron is of a good quality; but 
if fragments fly off, without any sensible indentation, the iron 
will be hard, brittle, and not to be relied on. It must, however, 
be remembered, that in a large beam of iron, different parts will 
often have different qualities, depending generally upon their 
situation in the mould. We recommend Mr. Tredgold’s book, 
as calling the attention of practical men to these and several 
other important subjects, which they are too apt to leave to the 
honesty or care of the iron-founder, but upon which every 
architect, engineer, and builder ought to be able to judge for 
himself. 
7. SreamM-Encine.—An Historical and Descriptive Account 
of the Steam-Engine, comprising a general View of the various 
modes of employing elastic Vapour as a prime mover in Mechanics ; 
with an Appendix of Patents and parliamentary Papers connected 
utith the Subject: by Charles Frederic Partington, of the London 
Institution, has just been published. This work, which is illus- 
trated by eight well-executed engravings, and several wood-cuts, 
contains a perspicuous and popular account of the principal 
kinds of steam engines now in use, and of the principles upon 
which they act; and although Mr. Partington has presented us 
with nothing particularly new or luminous in relation to his 
subject, he has compiled a book well calculated to instruct the 
unlearned in these matters, and not useless as a work of refer- 
ence to the proficient, from the selection of papers and facts 
which it contains. As such, we are happy to announce and re- 
commend it to our readers. 
8. Steam-Engine Chimneys. 
- To the Eviror of the Journal of Science, &c. 
STR, 
In a former number of your Journal, (No. 24, p. 352,) 
a suggestion is thrown out, that chimneys, in other respects 
equal, emit smoke in quantities greater or less in proportion to 
their height. 
The object of this communication is to furnish you with a 
more direct illustration of the truth of that remark, than either 
of the examples cited in the Journal affords. 
In passing through the town of Durham in the winter of 1815, 
my attention was attracted by a chimney of unusual height, 
situated at some distance from the town, and on the opposite 
