1838] 



FARMERS' REGISTER, 



279 



A contrivance for more ronipU'tcly covciinii' <li(^ 

 pped consists in nddinii; sovcral short chains to ihc 

 iiriil, wiiic.h, hy draiXirini;^ after it, upon tlic seed; el- 

 fcctually ralce tlicm ii\. Unlike a toothed harrow, 

 these ciiains do not heconie obstructed by sticks, 

 straw, &c. 



In most drills, ilie dropper immediately (()llows 

 the wheel ; but in some it precedes it, the wheel 

 beinjj mnde broad serves as a roller to press the 

 soil upon the newly sown seed. 



The chief difference in drills, that which con- 

 stitutes the chief variation in the different patents, 

 and which is still least perfected, is the contrivance 

 tor droppinn; the seeds evenly from the hopper. 

 In one of the simplest, the vessel for holdinn: the 

 seed, is a short cylinder with a horizontal axis, 

 made of sheet tin, and with a number of holes in 

 its circumference for the seed to pass through ; this 

 cvlinder is kept constantly revolvin<i by the motion 

 of the drill. An improvement in this, consists in 

 makinf^ the seed box of the shape of a very short 

 cylinder terminated at each end by a cone; and 

 the dropping part consists of a separate ring or 

 short open cylinder of tin, sliding closely on the 

 cylindrical part of the seed box. Several rings, 

 with holes of different sizes, for different kinds of 

 seeds, may be thus used on the same machine. 

 Rotary motion is given to this cylinder in two 

 ways. In one the machine has two wheels, the 

 seed box being placed on the axle between them 

 and revolving with them. This is recommended 

 fiir its great simplicity. In the other, a strap 

 passes from a small wheel on the axle of the main 

 wheel, to another wheel on the axle of the seed 

 box. The motion of the seed box may be in- 

 creased or diminished by varying the size of the 

 strap wheels. This contrivance is well adapted 

 to sowing all kinas of round smooth seeds, as tur- 

 nips, peas, &c. 



In another contrivance, a circular brush, kept 

 constantly revolving, sweeps against the seed 

 holes, and keeps them from becoming clogged by 

 driving the seed through. In Robbin's planting 

 machine, this principle is modified by substituting 

 a snapping wire spring for the brush. This is 

 adapted to irregularly shaped seeds, as mangel 

 wurtzel and corn. But it is liable to get out of or- 

 der. A simple and certain method of throwing 

 out these seeds evenly, is yet a desideratum. 



J. J. T. 



From the (London) Mechanics' Magazine. 

 smith's ever-pointed stone-cutting 



CHISEL. 



The ordinary chisels used for dressing and cut- 

 ting-stone very frequendy want sharpening, which 

 is an operation requiring time, judgment, and ex- 

 pense; having,' when blunted, to be forged and 

 sharpened and afterwards hardened and temper- 

 ed. A machine-maker of the name of Smith, in 

 this town, has lately invented an ever-pointed chi- 

 sel, which will, I think, soon be generally adopted, 

 provided it be made cheap. It is in (act an ap- 

 plication of the principle upon which JNlessrs. 

 Mordans' (or rather Mr. Hawkins') ever-pointed 

 pencil is constructed. A thin plate of Avell tem- 

 pered steel, of the width of the chisel required, is 

 placed between two cheeks of iron and held 

 tightly between them, by means which I shall 



descibo. The point of the thin steel project- 

 ing beyond the ends of the iron cheeks, Jbrms 

 the cutting edge of the chisel; and as soon as 

 the edge which projects is worn away by the 

 friction of the planing stone, the steel is ad- 

 vanced between the cheeks, and the edije is 

 thus immediately renewed. To prevent the steel 

 plate from slipping sideways, there are studs 

 on each side of it, on one of the iron cheeks, 

 which go info corresponding holes in the other 

 cheek. The whole is held toiretlier by a col- 

 lar or mortise slipping over, and hammered up 

 liirhtly, the cheeks being of a werlge shafx'. 

 When the mortise, or collar, is driven properly 

 home, a groove therein coincides with a groove in 

 the cheek of the chisel, and a wedge being put 

 into the hole thus formed, holds the whole chisel 

 tight; and prevents the mortise from being shaken 

 off by the blows of the mallet. 



At the top of each cheek, on the inside, is the 

 half worm of a screw; between these, a screw is 

 inserted, the end of which touches the top of the 

 steel plate; and on being turned dovvn with a 

 screw-driver, or otherwise, forces the steel out 

 liom between the cheeks for renewing the work- 

 ing edge. 



1 hope I have described the thing clearly enough 

 to be understood by my brother masons and your 

 readers, without the aid of a drawing: my hands 

 are too rough and stiff with handling the mallet and 

 chisel, and moving our hard native stone, to at- 

 tempt the draughtsman. 



I am, Sir, yours respectfully, 



A Stom:mason. 



Bradford, Yorkshire, Nov. 2S, 1S37. 



From the (London) Mechanics' Magazine. 



EFFICACY OF LIGHTNING RODS, OR CON- 

 DUCTORS. 



By F. Maccrom. 



I perceive that a question is mooted at the 

 meeting of the British Association for the Ad- 

 vancement of Science, whether in the case of a 

 certain "monument 140 feet high, erected on the 

 summit of a mountain 1,400 feet high, augmented 

 safety or danger, would be the consequence of 

 attaching to it a conductor or paratonnere '?" 1 

 am induced to call the attention of your intellec- 

 tual readers to this passage, as I am very sure that 

 the subject is of great iirqiortance to society. 

 About six months ago (vol xxvi. p. 367) you ho- 

 nored me by giving insertion to my account of a 

 safety gunpowder magazine, in which I speak of 

 lightning conductors, and to which I would request 

 your readers to refer. There is just now a gentle- 

 man, one Lieutenant Green, of the Royal Navy, 

 who is endeavouring to convince the public by 

 his writing, that conductors are prone to cause the 

 damage they are intended to avert. I must say, 

 that I regard this statement as a mischief^ for I 

 have seen too much of the saving power of conduc- 

 tors not to wish that every house in Great Britain 

 were protected by one. 



Lieut. Green, in his anii-paratonnere pamphlet, 

 lately published by Tanner, of New Bond street, 

 tells us of fifty churches in this country having 

 been lately struck by lightning, because they had 



