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November, 1919 at the joints. The other parts are of copper and brass protected with a heavy coating of tin where they come in contact: with the water: 'The re- sultant product is aerated and equally as cold as the inflowing water supply. The device makes use of the well known distilling principle wherein the water is heated to boiling point by steam coils. The vapor arising is condensed and as the impurities in the water do not vaporize, it is readily seen that they do not pass over into the condensation part of the appara- tus. These stills are in use on a num- ber of Great Lakes vessels. Engine Alarm In making landings and in passing through locks, it is of the utmost im- portance for the navigating officer to be certain that the orders sent through the engine room telegraph are prop- erly received and carried out. Thus, if the telegraph is moved to full speed astern he should know for a _ cer- tainty that the engine is promptly re- versed.. Instances wherein the _ tele- graph has -failed. to work are on record, one such accident causing a lake vessel to smash through a canal lock. This resulted in her going over the sill sustaining severe damage to her bottom. To eliminate accidents of this kind and to make sure that the engine is running as directed by the man on the bridge, the engineers of the Pitts- burgh Steamship Co., Cleveland, de- veloped the engine alarm shown in Fig. 14.. The 'engine rock shaft. is equipped with an electrical connection which makes contact with an electric terminal in both the go-ahead and astern positions. The telegraph in the engine room is also equipped with hee FIG. 10--CONDENSER WITH FOUR COMPARTMENTS ARRANGED FOR READY CLEANING tds THE MARINE REVIEW twe terminals so arranged that when i moved to designated speeds astern, an _ electrical connection is made which rings a bell in the engine room and a buzzer in the pilot house until the order is carried out. The same result is true if the telegraph is set at ahead positions when the en- gine is running astern. Electrical cur- rent is supplied by four dty cells. This device has been installed on all the vessels of the Pittsburgh fleet. Boiler Water Circulator In operating Scotch marine boilers it is of the utmost: importance that the inside of the boiler be kept clean, otherwise mud and sludge' will ac- cumulate on the heating surfaces to the detriment of efficient operation. The device shown in Fig. 15 is an appliance designed to keep the water in boilers of this type in constant cir- culation. It utilizes the common prin- ciple that water readily rises as it 11--LONG DISTANCE COINCIDENCE RANGE FINDER FIG. becomes heated. Thus in a Scotch boiler, where the water is not of an even temperature throughout, due to the fact that the water directly over the furnaces heats first, the law of gravitation is utilized. Utilizes Well Known Principle The valve chamber in this device is situated in the top of the boiler to which is fitted the conductor pipes. Thus it soon absorbs heat from the surrounding water. This heat is con- ducted to the water contained in the valve chamber with the result that this water starts to expand in volume and as its specific gravity changes, it Sil FIG. 12--AUTOMATIC STILL FOR FURNISHING - PURE DRINKING WATER finds its way out of the discharge port in the top. of the valve chamber. The water thus expelled is replaced by the water in the conductor pipes which lead to the bottom of the boiler. Thus it is readily seen that there will be a continual circulation of water as long as there is a difference in tem- perature, between the bottom and the top. of the 'boiler. When the operator desires to stop the circulation in the boiler it is only necessary to move the pointer to the FIG. 13--HOW THE COINCIDENCE Is MADE position marked: Circulator closed. It is pointed out that this feature is of especial value when operating in harbors, rivers and shoal water, par- ticularly when vessels are stirring up mud with their propellers. The device is operated as follows: First, the main blowoff valve is opened...Then the handle on the valve -- shaft is turned until the pointer is even with number one on the dial