326 



CRITICAL NOTICES OF NEW PUBLICATIONS. 



These experiments, which were favourable, were made upon the appa- 

 ratus shown in the annexed figure. A B is a section through the top 



of a boiler ; C D is the flue, 

 or fire-place, to which the tube 

 R L is supposed to be fastened 

 at the bottom, the flue closing 

 the tube. The lower part, H I, 

 of the tube contains a small 

 quantity of fusible metal, by 

 which a stem, L K, is soldered, 

 as it were, to the flue. The 

 weight, M, upon the lever, 

 P K, tends to draw the stem, 

 K L, upwards, and, when the 

 fusible metal is softened, will 

 actually disengage the stem. 

 The weight, M, descending, 

 rings the bell, N, giving notice that the proper limit of temperature 

 has been reached. If by throwing cold water into the boiler, which 

 at this temperature may be done without danger, or by other appro- 

 priate means, the temperature of the flue is reduced, the stem, K L, 

 having previously put in its place, is soldered again to the flue, and 

 the weight, M, being applied to the lever at P, the apparatus is ready 

 for action.* 



The second cause assigned for the undue heating of parts of a 

 boiler is the accumulation of sedimentary matter upon them. To 

 this the boilers of steam boats plying on the western rivers of the 

 United States are stated to be particularly exposed, those waters con- 

 taining both mud and calcareous matter in great abundance. The 

 facts brought together, from different quarters, in relation to sedi- 

 ments from salt water, from river water, and spring water, are inter- 

 esting. They are examined with a view to the application of vari- 

 ous remedies which have been proposed to the Committee, none of 

 which, however, are considered as proper substitutes for frequent 



• On this apparatus, the Magazine of Popular Science has these remarks : 

 **No doubt ! there can be no doubt of this effect occurring, the most perfect 

 fluidity mav be obtained ; but cui bono ? — for what purpose ?" We can 

 scarcely understand how an individual should be so dull, the mode of action 

 seems level to so mean a capacity. Perhaps our cotemporary was not aware 

 that letting off" steam was not always the " true remedy" to the danger of 

 an overheated boiler. Perhaps he did not see that the same power which 

 rings a bell, will equally open a valve or turn a stop-cock, if required, and 

 that if a large opening is not preferred to be made it is not without cause. 

 Here is his note on the subject ; it may be taken as a specimen of his fairness 

 and of his style : "We cannot help thinking that the following parallel case 

 of a '* true remedy" would be prescribed by the Sub-committee, if the ques- 

 tion were presented to them. Suppose a man has a box which can only be 

 opened by a certain crooked sixpence ; what is the best way of being sure to 

 have the sixpence always at hand when wanted ? Ansver. — Shut it up in 

 the box ! enclose the metal in a case /" 



