NEW ENGLAND FARMER. 



51 



pool, for a railway to cross the Mersey, and thus 

 connect Birkenhead and Liverpool, for all kinds of 

 transit. 



Mr. t'unninghain proposes to sink an iron tube 

 in the bed of the river, buried so completely below 

 the surface thereof that there would be no more 

 obstruction to the currents than at present. The 

 tube would have perpendicular sides and an arched 

 roof. It would be placed in a prepared bed, and 

 would be protected outwardly by various contri- 

 vances. Internally there would be two lines of 

 rails running on each side of the tube, with a pas- 

 sage in the middle for pedestrians. The entire 

 work, it is estimated, would not cost more than 

 £250,000.— Boston Journal. 



CHIMNEYS. 



Of all the minor evils which flesh is heir to, 

 there are few which so certainly bring tears into 

 every one's eyes as smoky chimneys. A man of 

 nerve may steel his heart against a great mis for 

 tune ; he may make no outward signs at the reci- 

 tal of griefs which would rouse a stoic; but take 

 him into a room where the chimney does not draw 

 well, and though he may be, like Othello, "Unused 

 to the melting mood," he will find himself exhibit- 

 ing all its outward signs, while his heart, strange 

 to say, is growing harder every moment. 



That both country and town houses are more or 

 less afflicted with this nuisance is abundantly 

 proved by the chimney pots and ventilators — odious 

 in the eyes of architects — which deform the tops 

 of so many chimneys every where ; and there can 

 be no doubt that the multiplication of stoves in par- 

 lors and sitting-rooms, of late years, is also owing, 

 in no snjall degree, to the apparently unavoidable 

 evil of smoky chimneys. Is there any certain 

 remedy for this evil? We answer yes. The 

 difficulty arises, in almost every instance, solely 

 from want of knowledge of the first principles of 

 construction, in the bricklayer who builds the 

 chimney. We have conversed with dozens of 

 mechanics, and have found but two who knew any- 

 thing of the principles in the matter, or whose 

 practical knowledge did not actually lead them to 

 build chimneys that must inevitably smoke, in 

 every situation exposed to downward currents of 

 air. 



The reason why chimneys draw at all, is the 

 natural tendency of heated air to rise ; smoke be- 

 ing much lighter than common air. Hence, the 

 warmer the flue, and the smoke which it contains, 

 the better the draught. For this reason a fire 

 lighted in a cold chimney in an interior wall of a 

 house, is more likely to draw well than one 

 built in the exterior wall — the cold of the open 

 air robbing the chimney of a part of its heat. 



The cause of smoky chimneys, however, is their 

 imperfect construction at the throat and the top. 

 If a flue, as is most commonly the case, is built of 

 uniform size, from the throat where the smoke en- 

 ters to the top where it escapes, it is evident that 

 there is a column of heated air in the flue of uni- 

 form size from top to bottom. Whatever offers 

 resistance to this column at the top acts equally 

 upon the whole, because the size of the column of 

 smoke at the top is precisely that at the bottom. 

 Now the resistance is that of a current of wind 

 upon the top of the chimney. Every time this 

 current of wind strikes, in a direction more or less 



downward upon the top of the chimney, a quantity 

 of smoke is driven out of the throat below. 



Let us now suppose that with a flue of the same 

 diameter, both the top and the throat are contract- 

 ed. The effect of this, in the first place, is to 

 break the force of the adverse current of wind ; 

 and in the second place, to divide the shock be- 

 tween the size of the opening at the top and that 

 of the whole column of heated smoke in the flue. 

 The effect this will have may be illustrated by 

 supposing a canal, with a gate or opening at the 

 end. Raise this gate across the whole width of 

 the canal — the water flows out. Stop the gate 

 suddenly, and we give a backward motion to the 

 water, in the whole breadth of the canal, many feet 

 distant; but stop it by a gate only half the width 

 of the opening, and we diminish this shock greatly. 

 Now make another narrow passage the width of 

 the small gate, fifty feet behind the gate, and we 

 shall find that the shock of shutting the gate di- 

 vides itself in a great degree among the particles 

 *>f surplus water, which makes the difference be- 

 tween the mouth of the gate and the width of 

 the canal behind it. Let the first gate represent 

 the construction at the top of the chimney, and we 

 have the parallel. 



The principle, then, of building chimneys to 

 draw well, is to contract the openings both at the 

 throat and the top, so as to break the force, with 

 which the wind (or even the air itself in some 

 states of the atmosphere) opposes the ascent of the 

 smoke. — A. J. Downing. 



A. Perforating Machine. — The tunnel of the 

 Troy and Greenfield Railroad, through the Hoosac 

 mountain, is made with one of Wilson's stone- 

 dressing machines. This machine is worked with 

 a steam engine, and will enter from six to fifteen 

 linear feet per day. The cutters are circular plates 

 of cast-steel, of 14 inches diameter, half an inch 

 thick, and ground, with a bevel on each side to an 

 edge. They are placed on the rock, at the angles 

 of about 45 degrees, and roll over the surface with 

 great rapidity. The edge is pressed into the rock 

 with'great force and acts as a wedge, prying up 

 and throwing off the rock in a surprising manner. 

 A block of granite, ten feet long and four feet 

 wide, was placed on a carriage, and submitted to a 

 single cutter, guaged to cut two inches from its 

 surface It passed over the entire stone in 22 

 minutes, and cut oft' 1600 lbs. of rock, leaving the 

 same as smooth as any hammer-dressed stone. — 

 Albany Argus. 



Iron Buildings.— Brick, says the Philaledphia 

 Dispatch, is cheaper than iron for buildings ; iron 

 is cheaper than brown stone, and the latter is cheap- 

 er than marble. Iron is yet a new material. The 

 patterns for castings are the most expensive parts 

 of the cost. After a while, when an infinite varie- 

 ty of patterns are made, which will suit all tastes, 

 iron will be as cheap as brick. 



New Patents. — Week ending Dec. 16. Eli- 

 hu and Warren W. Butcher, of North Benning- 

 ton, Vt., for improvement in weavers' temples. 

 David H. Richards and Joseph F. Flanders, of 

 Newburyport, Mass. for improvement in rotating 

 tumbler locks. Joseph W. Thorp, of South 

 Ware, N. H., for improvement in apparatus for 

 pressing garments. 



