NATURAL PHILOSOPHY. 173 



sealing-wax rather more than 1,000 pounds to the square inch; 

 the deficiency in the latter is attributed to the diminished quantity 

 of lac used in the composition. The cohesive force of solid glue 

 was found to be 4,000 pounds per square inch. 



IMPROVED STEAM GOVERNOR. 



At a recent meeting of the Massachusetts Institute of Technol- 

 ogy, Mr. R. K. Huntoon exhibited and explained his patent gov- 

 ernor for steam and water power. 



The centrifugal or ball principle, adopted in the old style of 

 governors, is in this entirely abandoned. The regulating weight 

 is raised in a vertical line, and the valve-lever is sustained as 

 easily at one point as another, by the action of a propeller re- 

 volving in a cylinder filled with oil (a mixture of lard-oil and ker- 

 osene), whose movements in a horizontal plane regulate the action 

 of the steam valves. The speed of revolution, by this ingenious 

 and novel arrangement, is the same whether the pressure of steam 

 be 30 or 70 pounds, and whether the engine be heavily loaded or 

 running light. The simple removal or addition of small weights 

 will cause the engine to run slower or faster, the adjustment being 

 speedily effected. However violent or sudden may be the changes 

 in the work done by the engine, an experience of several mouths 

 shows that this governor maintains the uniform speed at which it 

 may be set. It is noiseless and safe, as there are no revolving 

 balls. 



The importance of uniformity of action in steam machinery can 

 hardly be over-estimated, and none of the usual forms of ball 

 governors have hitherto secured it. There are, however, some 

 recent French modifications of this kind of governor, especially 

 that of Farcot, which secure an unvaiying height for the cone of 

 revolution, and thereby a uniform velocity in all degrees of diver- 

 gence of the balls ; this, as reported on by Prof. Tresca, bore ex- 

 treme changes of motive power and load without alteration of 

 velocity. 



The Huntoon governor may be expected to be especially valu- 

 able for marine engines, as the rolling of the vessel would not 

 affect its action, and the pitching would hardly be noticed in so 

 short a space as it occupies amidships. It acts equally well in its 

 horizontal and vertical form. 



TESTING IRON BY MAGNETISM. 



The English engineering journals contain an exceedingly val- 

 uable paper, by Mr. F. A. Paget, C. E., upon a method of detect- 

 ing faults in iron forgings by means of an examination of the bar, 

 shaft, or whatever the work may be, with a magnetic needle ; and 

 not only does this method detect a fault in the welding, but it indi- 

 cates the change which so often occurs in iron from the fibrous to 

 the so-called crystalline condition. The extreme value of this 

 discovery will be fully appreciated by all persons who have deal- 

 ings with shafting, iron wheels, and axles, and the various com- 

 binations of machinery which depend entirely for safety upon the 



