6$ THE BEAMS OF STEAM ENGINES, 



II. 



On the ConjiruStion of the Beams of Steam Engines. By ftfc 

 J. C. Hornblower. From the Author. 



Dear Sir, 



! 



Hiftortcal intra- 1 BEG leave through the means of your Journal, to lay be- 

 fore the public an account of the framed lever mentioned at 

 the clofe of the article Carpentry in the fupplement to the 

 Encyclopedia Britannica, as it was originally defigned for an 

 engine to have been ere&ed at Amfterdam in the year 1776, 

 together with two others, potfefling every poffible advantage . 

 of levers confiding of fmall fcantles. 

 The fram«d le- I know not by what means the lever above referred to 

 fcVibeTnecds no come to ^ e con ft m & e d with the difadvantages intimated by the 

 hole bored in it. writer of that article, but there is no neceffity for a hole to be 

 Other particu- bored, or a bolt to be driven in any part of the framing be- 

 tween the arches, except for the chain ilays. The wedges a, 

 b, Fig. 1, Plate V. thus applied, would be an improvement, 

 for want of which a lever of this fort in the hands of a negli- 

 gent engineman had one of its joggles forced off, the ihoulder 

 of the tennon, which was morticed into the arch, not being a 

 joint by the eighth of an inch, or more ; but when it met with 

 the arch it went no further, and continued to work for many 

 years under a great load, and much to its difadvantage in other 

 refpecls. 

 Dimenfions of a The length of this lever was 21 feet, the fcantles were 12 

 lever oF indiffe- inches by 6 ; height of the whole when put together 30 inches,. 

 &;« and leverage on the gudgeon as 4 to 3. This laft circum- 



itance operated much againft its conftruction, by giving addi- 

 tional force againft the joggle at that end, but had it been 

 framed fix inches higher, I doubt not but it would have flood 

 to this day under all its difadvantages. 

 Scantlesand The fum of the fcantles is 18 by 12, area of the fecticn 2)6 



Ioad ' inches, column of water in four lifts 4800 lb. with 440 fathoms 



of rods, (pump rods) which with the appendages on the other 

 end, added to the power necefiary to overcome the refiftance, 

 amount to about feven tons. 

 Another con- But a much fimpler, and in fome refpecls a more advan- 

 ftrucTion Fig. 2, tageous mode of framing is (hewn a,t Fig. 2, and may be con- 

 W€Ujnadc * ftruaed 



