PREFACE.

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apparatus. I have therefore begun the work with an at-tempt to remove this impediment; to procure, at a smallexpence, a commodious and easily manageable set of fur-naces, &c. which may be all worked under a commonchimney, and some in the middle of a room without offence,and with which most of the operations, that require theassistance of fire, may be performed, in the way of experi-ment, with great ease, expedition, and safety : if those,who have been accustomed to the common larger and moreexpensive furnaces, should at first be at any loss in the useof these small ones, a very little practice and attention willremove all difficulties, and convince the operator of theconvenience which I have long found from them in expe-rimental pursuits, for which alone they are designed. Thestructure and management of the large furnaces, kilns,Lee.used in different businesses, are intended also to make partof this work, and mechanical contrivances of other kindsare likewise occasionally considered, with a view chiefly torender them more simple, convenient, or effectual. Inthe present volume I have given an entire essay on the im-provement of the machines for blowing air into largefurnaces, &c. by a fall of water, without moveable bellows,in virtue of the water carrying down air with it in fallingthrough pipes ; and I have the pleasure of being informed,by a foreign correspondent, of a machine which he hasconstructed on the principles there established, which an-swers as well as can be desired.

It would be needless to specify in this place the severalmatters contained in the volume ; a list of them may be

seen