Journal of Agriculture. [8 Jan., 1907, 



V 



a perfectly tight joint can be easily made. Doubtless many have at times 

 experienced a great difficulty in making joints on flanges, which are sup- 

 posed to be cast to the circle of the boiler, but which, in the majority of 

 cases, do not fit correctly. These seatings are sometimes objected to on the 

 score of expense, but the money would be better expended on seatings than 

 in attaching domes, which, besides being often useless appendages, weaken 

 the boiler by requiring so large a hole to be cut in the shell. The seating 

 used for the man-hole dooT would also strengthen that part of the boiler 

 round the man-hole door. 



Water Gauges. — Glass water gauges should be fixed on every boiler, 

 and the best plan is to have two on each. I consider wheel scavenger cocks 

 I0 be the best — especially where bad water is used. I have known the com- 

 mon plug cocks require grinding every week, and they have only lasted 

 a short time. When these cocks have been replaced with scavenger cocks, 

 the latter have worked under exactlv the same conditions as the foxmer for 

 \ears, and have not required to be ground. In many cases I have found 

 the glass gauges fixed too low down on the front of the boiler, and some 

 of them would show water in the glass when it was off the top of the tube. 

 This is a most dangerous position in which co have gauges fixed. The 

 bottom mountings of gauge glasses should never be fixed lower than 2 inches 

 above the highest part of the tube; this would give about 4I inches of 

 water over the tube when the water was at the lowest visible point in the 

 glass. 



Try Cocks. — The bottom try cocks sho'uld be fixed at the level of the 

 bo'tcom of the glass, and when there are 4 inches of water over the tube, 

 the bottom try cocks should blow steam. By fixing the cocks at this height, 

 if through any cause the water should disappear from the glass, there 

 \Tould be no danger as long as water came out of the bottom cock of the 

 gauge mountings, but as soon as it is below the bottom cock the driver 

 should draw his fires. There are several automatic appliances to give warn- 

 infj when the water is gettimr too low in the boiler, one of the most generallv 

 used being a float placed inside the boiler, and connected with a steam 

 whistle. When the water gets too low the float opens the whistle. None 

 of the appliances have, however, come into general use through their liability 

 to get out of order, and if thev were depended upon thev might prove a 

 .source of danger instead of safety. All the taps should be tried several 

 times in each shift, and pipes should be fixed to all of them so as to carry 

 the water clear of the boiler front. 



Safety Valve. — The safety valve should in all cases be large enough 

 to admit of the escape of all the steam which can be generated in the boiler 

 without raising the pressure at which the valve is set more than 12 per cent. 

 The safety valve most used is the lever valve. This lever should not press 

 down the valve by a projection welded on the under side of the lever, nor 

 should it be fixed so as to press directly on the top of the valve, but th':^- ' 

 should be a loose pin under the lever, and secured thereto with a double e\ e 

 and bolt. The pin should be pointed to fit into a countersink on the top 

 of the valve ; it should bear onlv on the point, and be clear of the counter- 

 sink everywhere else. This plan does away with the lateral thrust, which 

 is mostly caused by other arrangements. Care should be taken that the 

 nins do not get rusted, that they work freely, and that the guard over the 

 lever (which is placed opposite the fulcrum) does not press- on the side of 

 the lever, as is sometimes the case, and an increased pressure thereby put 

 on the boiler. Lever safety valves are easily tampered with, as in many 



