76 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[March, 



REEFING STEAM-BOAT PADDLES. 



Fig. 1. 



Fig 



V.W, Pivot wheel. S, Sli:ilt. 



Sir — Obseiviiig by sumc of tlie public jounr.ils that the rcpfing of 

 ste:iin-bont jjaddlos is buc-uiniiig a matter of interest, I take the liberty 

 of sending a rough copy of a sim]ile method executed by Messrs. 

 Boulton, Watt & Co. for a vessel on the Tyne in the year 1H15 (whose 

 drauglit was variable,) it was found to answer well. 



The extreme diameter when the boards were out, was II ft.; by the 

 mode adopted, they could be drawn in 7i in., reducing the diameter 

 to U ft. 9 in., which was considered sullicient for a vessel of only 5 feet 

 immersion. 



By the application of a lever, the whole of the boards were moved 

 at once, and fixed in the required position Ijy a screw pin ; this in- 

 volved going into the paddle-box to make the adjustment previous to 

 starting, but the operation is capable of being performed by a pinion 

 working into the internal circumference of the pivot wheel (shewn in 

 the small side figure), while the rpiantity of reefing may be carried to 

 all necessary extent by enlarging its diameter. 



It was the fashion in those early days of steam navigation to fit the 

 wheels with shrouding, which, although not necessary to the scheme, I 

 have chosen to show it as executed at that period. Should you con- 

 sider this worthy of insertion, you will oblige. Sir, 



Your constant reader, 



London, 20lh January, lb40. T. Z. 



PATENT IMPROVED BOILER OR APPARATUS FOR 

 GENERATING STEAM. 



The first part of my invention consists of an apparatus (after de- 

 scribed) for causing water in the state of dew, or divided into very 

 minute drops or particles, to descend slowly through the interior of 

 the boiler or generator, upon the heated surface of which, so much of 

 it as is not converted into steam during its descent, ultimately falls ; 

 by which means a less quantity of heat is abstracted during any given 

 time from the heated surface, than if such surface were covered with 

 a continuous sheet or film of water, or witli a boily of water, as in the 

 common boiler. And by the means I adopt, I do not merely raise 

 steam, by wetting the heated surface, but the boiler or generator when 

 at work is filled by dew or water in a state of minute division, w'hich 

 in its descent, becomes partially converted into steam, by the heat of 

 the atmosphere or vapour within the boiler itself. 



I find that a temperature of 50(1" or thereabouts, of Fahrenheit, in 

 the body or substance of the boiler or generator, is that best adapted 

 to the purpose of raising steam. 



Another part of my invention consists of a self-acting apparatus, 

 (afterwards described) for regulating the supply of water to the gene- 

 rator or boiler, according to tlie condition of the heated surfaces, and 

 the consequent force of the steam wdthin the boiler, that is to say, that 

 if the boiler contains a greater body of steam, or of greater elastic 

 force, than is necessary for the wants of the engine or other purpose 

 to which it may be applied, then by the self-acting apparatus before 

 referred to, the stroke of the force or supply-pump is shortened, so 

 that when the steam is high in the boiler, the quantity of water in- 

 jected becomes proportionably less; by this means, if by any chance 

 in consequence of the boiler becoming heated to redness, or to any 

 other degree of heat which would be highly dangerous in other boilers, 

 or from any other cause, steam of a violently elastic force be produced, 

 its etfect is, through the medium of the above regulating apparatus, 

 to shorten, or totally shut otl", the supjily of water, until the surface 

 becoming cooler, or producing steam of less elastic force, the pump is 

 again allowed to act; such a case, however, can never happen, ex- 

 cepting after the engine has been standing still for some time, and 

 when, by neglect or design, the usual precautions and attention be- 

 stowed upon other boilers have not been observed, as the damper 

 regulator, which is somewhat similar in efit^ct to those in present use, 

 will always prevent the fire being in advance, or more powerful to 

 heat the surfaces, than the water to cool them. 



In applying this invention, it will be generally found desirable to 

 keep that part of the surface of the boiler, ex])osed to the immediate 

 and corrosive action of the fire, covered with water, by wh.ieh means 

 it \\ ill be prevented from burning, and another part of my invention 

 consists in a self-acting apparatus adapted to attain this object. By 

 this apparatus (which is hereinafter described) the water is prevented 

 from accumulating in the boiler beyond the quantity found best in 

 practice, and which, in the boiler I generally use, is from three to six 

 inches in depth over the fire ; this apparatus, at the same time that it 

 prevents the water rising in the boiler beyond a certain limit, acts 

 upon the force-]nunp in a way which will bo presently described, so 

 as to reduce the quantity of water injected, if necessary. 



In a]iiilying my invention, I employ n)eial flues, by which means the 

 fire is not only kept longer upon the surface, but the flues become 

 carriers or depositaries of heat, and by radiation iuqjart a certain por- 

 tion of the efl'ect of the fire upon them to the boiler, and thus econo- 

 mize fuel, besides adding to the strength of the boiler itself. 



Another ])art of my invention consists in forming ridges in the in- 

 terior of the boiler, by which the descent of the water over the sur- 

 face is retarded, but which, although a great improvement to the 

 action of the boiler, is not absolutely essential to it. 



The external figure or shape which I ha^e generally adopted as the 

 best in practice, will be seen by the accompanying figure; but any 



