156 APPENDIX. 



3. Morgan's Paddle Wheel. 



This wheel being of some importance on account of the extent to which it has already 

 been employed and its decided superiority over all others that have hitherto been used, and 

 having been very much misrepresented, we feel it necessary to be explicit in showing its 

 peculiarities of principle and construction. The Plates LXXXII. and LXXXII. a, are the plan 

 and elevations of the wheel of Her Majesty's steam frigate ' Medea,' of which the principal 

 dimensions are indicated ; but, as there are no letters of reference in these plates, we will refer 

 to Fig. 1. PI. LXXVIII., which is a diagram of Morgan's wheel intended merely to explain 

 its principle, and as a comparison with the other kinds of wheel of which similar diagrams 

 are contained in the preceding plates. The proportions of the parts are not such as are 

 given them by the manufacturer, Mr. William Morgan, being the same as those of the 

 common wheels in PI. LXXIV. The elevations of the 'Medea's' wheel will give the best 

 notion of Morgan's wheel, as made at present. 



This wheel is composed of the following parts : an iron frame-work, forming each side of 

 the wheel, consisting of a boss, represented in Fig. 1. PI. LXXVIII. by the larger of the two 

 circles described with the centre C, (the smaller one is the section of the shaft,) in the 

 circumference of which are keyed the arms, represented by the radial lines r, r, &c., and 

 these are united at their outer extremities by a polygon, S S S, made of round iron for the 

 sake of lightness ; there is also a smaller polygon, which is indicated in the figure but without 

 letters, and in large wheels two smaller polygons, as in ' Medea's * wheel ; these serve to 

 render the frames more compact and firm. The two frames are united together at the angles 

 of the outer polygons, as at S, by means of spindles firmly keyed to the frames, and by 

 diagonal stays of iron from the alternate angles of the smaller polygons, in small wheels, to 

 points situated on the opposite arms between the two polygons, so that, if one diagonal stay 

 departs from one of the angles of the polygon in the outer frame, and joins the inner frame 

 at a point between the two polygons, the next shall depart from the next angle of the 

 polygon in the inner frame, and meet the outer frame at a point on the opposite arm between 

 the two polygons, and so on alternately. In large wheels, where there are three polygons in 

 each frame, the diagonal stays are made in the form of a cross, joining all the angles of the four 

 smaller polygons two by two diagonally, as is seen in the plan of 'Medea's' wheel, PI. LXXXII. a. 

 Each paddle-board is bolted to a kind of frame of iron, called the stem (originally the bent 

 stem), of which the lever S G forms a part, and which is furnished with two steel bushes, 

 made to turn on steel collars fixed on the spindle, which are accurately turned and polished. 

 The stem-lever S G is fixed at any angle with the surface of the float which may be most 

 convenient, that, as well as its length, having very little influence on the motion of the float, 

 and none at all, within certain limits, on its inclination as it enters and leaves the water. In 

 order to leave room in the interior of the wheel for the machinery which is to guide the 

 floats, the shaft is only fixed to the boss of the inner frame, and does not pass through as in 

 other wheels ; this does not, however, much affect the solidity of the wheel, for the diagonal 

 stays make it nearly as strong, if not equally so, with no more weight of metal than there 

 would be in the piece of shaft which is dispensed with : in practice, at least, no deficiency of 

 strength has been experienced on that account. The guiding machinery consists of a crank, 



