TRANSACTIONS OF THE SECTIONS. . 199 



of which the Driver is unaware, such, for instance, as a broken axle, or a carriage 

 getting oif the line. 



6th. The power in hand should be susceptible of easy modulation that the Driver 

 may be able to apply a moderate amount only for effecting ordinary stops, whilst 

 he keeps in reserve a proper excess of power to be used only on emergencies, or on 

 the contingency of slippery rails. 



Gth. Full break-application should not require more than a very moderate effort 

 OH the part of Driver or Guard. 



7th. The pressure should be steady and distributed as equally as possible over all 

 the wheels, and acting upon them with the intervention of some elastic medium to 

 prevent too suddeu and violent action, which might occasion the snapping of 

 chains or drawbars, and tend to inconvenience the passengers. 



8th. The machinery should be of simple construction, not likely soon to get out 

 of order, and admitting of being easily repaired. 



9th. Indication should be constantly afforded to Driver and Guards that the brakes 

 are in a proper condition to work or otherwise. 



10th. The power of working the tender brake and the van brakes by hand, as 

 well as by power, may be advantageously retained. 



11th. The brakes to be self-acting in case of severance of the train, and when 

 Severed the Guards to have control over the severed portions. 



12th. Automatic action being provided, means should be furnished to the brake- 

 attendants for modifying that action instantaneously, according to the circumstances 

 in which the trains may be placed after an accident has occurred. 



13th. It would be dangerous, and therefore unadvisable, to give to passengers any 

 power over the brakes. 



Such seem to be the principal conditions necessary for realizing the conception 

 of a perfect brake ; and these, when carried into practice, and combined with the 

 power of applying at will a force which, inclusive of the friction of the train, 

 should amount" to 10 per cent, of its weight, would constitute an invaluable instru- 

 ment in the hands of our train-attendants for use under contingencies of almost 

 daily occurrence at some place or another of the great network of railways which 

 covers this country. 



On the Experiments of the Boiler Committee of the Admiral/]/. 

 By Captain Avnsley. 



On the Preservation of Iron. By Professor Barff. 



On the Upward Jets of Niagara. 

 By W. H. Barlow, V.P. Inst. C.E., F.B.S. 



When visiting Niagara last year, after acting as one of the Judges at the 

 Centennial Exhibition at Philadelphia, 1 observed certain physical effects connected 

 with the Great Falls to which I desire to draw attention. 



First. It was observable that the doors and windows of our hotel, unless tightly 

 closed, were subjected to a jarring movement, the impulses of which varied in time 

 and degree. 



- The hotel in question is "Clifton House," on the Canada side, the southern face 

 being parallel to and nearly opposite the American Falls, from which it is distant 

 about a quarter of a mile ; and its south-west corner is not far from being opposite 

 to the mean line of face of the Canada or Horseshoe Falls, the distance Deing 

 over half a mile. 



The windows of the hotel opened on hinges, and if tine of them was set slightly 

 open, and the observer placed himself in such a position as to see the reflexions of 

 distant objects in the surface of the glass, the times and varying intensity of the 

 jarring impulses could be clearly observed. 



