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240 and consists of a wedge to each lev- er, which is inserted or withdrawn to change the time of dropping the valve. It is operated by a pendulum actuated through a sliding arm on the cross-head, the usual cam motion be- ing used for handling. Another ad- justable gear is that known as the Rees, which is used on many steam- ers built by the James Rees & Sons Co. Movement is obtained from the cross-head by pendulum, much. the same as in the California cut-off, "but the arrangement manipulating the valves differs. The builders have dif- ferent methods of applying this gear. In a more recent adaptation, the main valve gets its movement from a wrist and a small connecting rod coupled to the main pitman. This, through a rocker arm, operates the main valve, while the cut-off is actuated by a pendulum from the crosshead. D. M. Swain, of Stillwater, Minn., has successfully introduced many nov- elties in machinery for both stern and side-wheelers. His boats are reputed to. be. very fast and economical. 1 regret that I cannot submit drawings of the valve motion, which, like two or three others, takes its movement from the pitman. Mr. Swain's special- ty appears to be cross compounds for stern wheelers, the high pressure on one side and the low pressure on the other. In side wheelers he puts the high pressure forward of the paddle and the low pressure aft. This gives a more uniform effort to the wheel and greater economy. The' engines are of the inclined oscillating type. Messrs. Gillett & Eaton, of Lake City, Minn., have made improvements in steamboat machinery, using piston valves for both the main valves and the adjustable cut-off. The piston valves have snap packing rings. The engines are built simple, cross, or tan- dem compound. 'Mr. H. F. Frisbee, of Cincinnati, O., has done much in improving vari- ous valve gears for western river boats, and I am pleased to be able to submit beautiful wood engravings, showing a cylinder 15 in. in diameter, having 6-ft. stroke with poppet valve and special gear, which, it is claimed, works one-third stronger than the or- dinary lever engines. The receiving valves are 5 in. in diameter and the exhaust valves 6 in. diameter. These engines are installed in the stern-wheel boat Tacoma. She was built in 1897 and has done most excellent work. Wheel and Shaft. Stern and side paddle-wheels on the western rivers are almost always built THe Marine REVIEW August, 1909 Capt, W. J. Baxter, SeEcRETARY-TREASURER Society or NAVAL ARCHITECTS AND MarINE ENGINEERS. of wood, this material being more easily repaired. Iron frames are lighter and have other advantages, but for river use where there are submerged logs and rocks and frequently much float- ing timber and ice, the wheels are often damaged. A few spare wheel arms, braces and buckets are. carried and easily and quickly replaced at the first opportunity. The shaft, which is either iron or steel, the former frequently preferred, is hexagon throughout, except at the bearings and the seating for the cams. Three or more cast iron, or occasion- ally steel, flanges are keyed on the shaft. These have radial recesses on their sides to receive the wheel arms. These radial arms are braced at two or three points in their length and are further strengthened by curved sec- tions of flat iron bolting all up to- gether. The buckets are secured to the arms by stirrups and plates, so they may be slipped in or out slightly, | to better adapt the wheel to the power of the engine. ' The question as to the best dimen- sions and form of the paddle-wheel is a much mooted question. No single rule applies in all cases; in stern wheel the length is largely determined by the width of the boat, and the diam- eter is such as will give the desired travel when the are turning at the permissible revolutions. These in small and medium sized boats run from 258 to 35 R. P. M., in "fareer boats from 10 to 25 R. P. M. I under- tand the Sprague does most of her work at about eight revolutions, some- times less, As long-stroke, slow-mov- ing engines, when coupled to a shaft at right angles, do not balance, the wheels are built buckets of un- even weight and sometimes of engines with vari-