THE following Treatise contains the substance of a Lecture delivered before a scientific audience at the Royal Institution on the 11th March 1836, and which is now, by the addition of elementary illustration, fitted for popular use. My reasons for not ptiblishing it sooner were-first, that, in a matter of such importance to this and other countries, as t. he obtainment of necessary warmth, from failure with respect to which, and to ventilation, much of the suffering and many of the diseases which afflict the inhabitants arise, I might, in recommending changes, have to report the result, not of one or two experiments only, but of many, carried on under great variety of circumstances, and in all the seasons of the year. Secondly, that I might, by wider observation and discussion, be better prepared to make evident to popular apprehension certain misconceptions or prejudices which have hitherto prevented the introduction of better methods, and to explain to makers of the new apparatus what would be required of them. I know that, owing to the delay of the publication, not a few imperfect stows halve been made, by persons little acquainted with scientific principles, and who t hcrefore needed, for constant reference, written directions as minute and precise as are here given. But to have prepared such directions for any one maker, rendering myself responsible for his performance, would have cost me nearly as much time, which I could ill spare, as to prepare this book, which is to serve as a guide to all I therefore declined doing so, and advised persons generally to wait for the publication of the book. My reason for delivering the lecture before I had the book f6lly prepared, was, that as I had decided not to reserve for myself any patent right in the new apparatus, I might, by having numerous competent witnesses of what I had proposed and accomplished, prevent other parties who might hear of my processes from appropriating them by patents, and thus coming between me and the public. Because several of the new means, and particularly the thermometer stoves, are of the nature of the things for which patents are usually taken, friends had urged me strongly to follow the custom-representing that thelegislature of this country has devised the patent alone as a mode of remunerating the proposers of useful inventions and that many honoured names, as lately, of Watt, Arkvright, Wollaston, C., are in the list of thoselwho have profited by the law and further, that in the case of the stove, it would be an advantage to the public that I should retain the right of naming the persons allowed to manufacture it, thereby to prevent such disappointments from imperfect workmanship, as happened in some cases with regard to my hydrostatic bed, and other suggestions strictly professional. I had decided not to take the patent because the stove was originally planned as a means of preventing and curing diseases, purposes for which it will always be important, whatever other advantages be derived from it and in this country it is usual for members of the medical profession to make an offering at once to the public of any means for the benefit of the general health which they may dis cover or devise, without stipulating for private advantage... --This text refers to the Paperback edition.