120 LECTUEES TO SCIENCE TEACHERS. 



Persian made the mistake of supposing that the umbrella 

 was a necessary adjunct to a proposition for matrimony in 

 England, and waiting until he could get a propitiously 

 wet day for the purpose, lost his chance and the young lady. 

 I should have been ashamed to take up your time with 

 telling a tale such as this, had not a grave man like Mr. 

 Lowe thought it not incompatible with his dignity to offer 

 this story to the Political Economy Club as illustrating the 

 mistakes those foreign nations make, who, when wishing to 

 settle a question of tariffs, look upon a treaty of commerce 

 as the vital matter, and not as a mere adjunct, the fact 

 being that the treaty has no more to do with it than the 

 umbrella has in the proposal of marriage. As a fact, 

 however, when your mind is once possessed by an umbrella, 

 or a treaty, or any other thing, it is extremely difficult to 

 get free from it, and therefore when you had once, for any 

 reason, settled on a beam engine it was extremely difficult 

 to get rid of the beam and go to work without it. Besides that, 

 there really were many conveniences attending the use of 

 the beam; the different parts balanced each other, and beams 

 afforded a very convenient means of attaching the pumps, the 

 air-pump and the cold-water-pump and the feed-pump and 

 of making their respective strokes proportionate to the duty 

 required of them. It also, in olden days, was a convenient 

 means of working the plug tree which operated the valves 

 for admitting the steam and for exhausting it. The beam, 

 therefore, had very many conveniences, but we see that when 

 Watt closed the cylinder at the top and made the piston 

 tight without water-packing, one of the very first things that 

 occurred to him was that you might do without a beam at all, and 

 might use the direct action of the piston, by placing the steam 

 cylinder over the pit, and might by an invention of the 

 piston rod, raise the pump without the aid of the beam the 

 construction now so well-known as the Bull engine. But still 

 the beam remained for many years. It had, as I have said, 

 its advantages, and so long as we were using steam for 

 about Slbs. pressure above atmosphere (that was the pres- 

 sure when I was an apprentice), and with some 121bs. 

 vacuum ; and so long as we employed house-engines, the 

 beam being supported on girders built into the engine-house 

 wall (either into the side walls, or in the case of a pumping 

 engine into the end wall, the house only covering half of 



