and with the view hereafter to make the 

 Flora of the neighborhood complete, it is 

 particularly requested that information of 

 the discovery of any new or rare Plant, be 

 sent to the Editor, with the habitat and date 

 when gathered, accompanied, when con- 

 venient, by a specimen of the plant." 



This is the direct means of carrying out, 

 fully, the editor's laudable effort ; and we 

 trust the appeal will be responded to. 



The Steam-Engine. By Hugo Eeid. Illus- 

 trated by Forty Wood Engravings. Third 

 Edition, Enlarged. 12mo. Groombridge 

 and Sons. 



There need be little surprise that a volume 

 like this should speedily attain a third 

 edition. The low price, and popular form, 

 in which scientific works are now brought 

 before the public, ensure their success ; and 

 the publishers get their reward in the large 

 additional quantities disposed of. 



It will not do now, for any of us to plead 

 ignorance of the nature, object, and powers 

 of the Steam-engine. We meet one every- 

 where ; we hear it, we see it ; we sit behind 

 it, and it flies off with us at a rate that would 

 have driven our forefathers crazy. Still, 

 we have yet much to learn about its interior, 

 — how it is constructed, how it acts ; and 

 whereby it acquires its terrific powers for 

 good or for evil. 



All who are seeking for such information 

 must procure this book ; it will neither puz- 

 zle nor confound them. On the contrary, 

 they will find themselves materially benefited 

 and instructed. 



As we are great avowed advocates for 

 Popular Science, we have pleasure in bring- 

 ing under the eye of the general reader, the 

 following — 



Description op the Steam-Engine. 



The Steam-Engine is a machine for the pro- 

 duction of motion, in which steam (the vapor 

 of boiling water) is used. A machine (from the 

 Greek mechane, through the Latin machind) in 

 the sense now generally understood, means a 

 contrivance for applying to some object a continu- 

 ous and regular motion, as a spinning wheel, a 

 loom, a w r atch or clock. If we choose to extend 

 the term so as to include such contrivances as a 

 gun, a mortar, a bow and arrow, a sling, we 

 must at all events carefully distinguish between 

 those which give a continuous and regulated move- 

 ment, and those which give a sudden, irregular, 

 and quickly terminated impulse. The Steam- 

 Engine is a sort of primary machine, the object of 

 which is the production of force, or moving power, 

 by means of which continuous motion may be 

 communicated to other bodies — as the wheels of 

 a carriage ; paddles or oars for propelling vessels 

 on water; the rod of a pump for raising water; 

 grindstones for reducing bodies to powder; 

 machinery for spinning, weaving, turning, ham- 

 mering, boring, communicating pressure, &c. 



Motion is the general object of all machines • 



and, in every description of machinery, there are 

 two parts which must be carefully distinguished : 

 — First, The machinery which comes into im- 

 mediate contact with the substance : to effect some 

 change upon which is the ultimate object of the 

 operation ; Second, The engine, or great machine, 

 which sets that lesser machinery in motion. The 

 latter is called the first mover, first moving 

 power, or prime mover. The prime mover pro- 

 duces the motion; the secondary machinery ap- 

 plies it. 



In a common turning lathe, or in the case of 

 the hand-pump for raising water ; in the wind- 

 mill or the water-wheel for moving a grindstone ; 

 the man who, by his muscular power, sets the 

 turning lathe in motion, or works the handle of 

 the pump; the vanes of the windmill; and 

 the water-wheel — are the first movers. It is 

 in these that the motion commences — their object 

 being simply the production of moving power, 

 which has to be transmitted from them to the 

 machinery which comes into immediate contact 

 with the wood to be turned, the water to be 

 raised, or the corn to be ground. 



The steam-engine is a first or prime mover. 



In every case of the production of motion by 

 machinery, the first mover is simply an engine, 

 or machine, so constructed as to take advantage 

 of some natural properties of bodies which are 

 capable of giving rise to motion. In describing 

 the steam-engine, then, there are two things to 

 be considered: — First, Those natural powers 

 resident in bodies from which we procure a force, 

 or moving power; Second, The machine, or 

 engine, by winch those powers are made effective 

 for the general production of motion. We shall 

 first direct our attention to the former — the 

 source and mode of action of the natural forces, 

 which, in the steam-engine, give rise to the 

 motion. 



Infinitely various as the different kinds of 

 power may at first sight appear, and however 

 complex the machinery by which they are ap- 

 plied so as to produce motion ; upon analysing 

 them, it will be found that there are only three 

 sources from which we can obtain a force or mov- 

 ing power — animal strength, attraction, and 



REPULSION. 



Of these, the first and most obvious, and the 

 only one within reach of man in the rude or 

 savage state, — or indeed the only one at his com- 

 mand without considerable progress in the arts, 

 — is the muscular power of animals, or, as 

 it is frequently called, animal strength. This 

 source of power resides in the muscles — long, 

 fleshy bodies of a fibrous structure, fixed at each 

 extremity, and possessed of the property of con- 

 tracting (diminishing in length), in obedience to 

 the will of the animal. By this contractile 

 power, the more moveable of the points to which 

 the extremities of the muscle are attached, is 

 made to approach the other. These muscles 

 arc possessed of great strength, being capable, as 

 has sometimes happened, of breaking the bone 

 to which they are attached. We have familiar 

 examples of the application of this power, in the 

 plough, carts, and carriages, canal-boats, horse and 

 cattle mills, all set in motion, and continued in 

 that state by the contractile power of the muscles 

 of animals. * The muscular force of man himself, 



