1844.] 



THE AGRICULTURAL GAZETTE. 



593 



s 



FFD-WHEAT. — Any one desirous of obtaining 



c ' " at for use this autumn, may ascertain, by applica- 

 ~ 1\ tfc«» particulars of the crops of two excellent varieties — 

 ^h" reff? Hopetoun, and Morton's Red-Straw White, which have 



SSfSl ELD FABM, THORNBURY, GLOUCESTERSHIRE, 

 V . *l» last 3 years. This year's crop is on sale at 8s. a bushel. 

 SSWSW bitfield. 



^fje gterfcttltttral Alette 



SATURD AY, AUGUS TS!, 1844. 



MEETINGS FOR THE TWO FOLLOWING WEEKS. 

 Thu*idAT, Sept. "5J Agricultural Imp. Soo- of Ireland. 



Sept- 2 Usk. 



FARMERS' CLUBS. 



Sept* 10 Abergavenny. 



The economical value of any farm imple- 



MENT--if, for the moment, we disregard its cost price 

 —depends, first, upon its efficiency— i. <?., the degree in 

 which its work approaches perfection ; and secondly, 

 upon the expense connected with its use— i. e., the 

 horse-power and manual labour required in working 

 it. There are thus two subjects of inquiry connected 

 with every machine, viz., its construction, first, as 

 affecting its efficiency, and secondly, as affecting the 

 power required to work it. 



Let us take up the consideration of a particular 

 class of implements ; the first to which our attention 

 is naturally due are those of cultivation. All these, 

 including draining-ploughs, subsoil-ploughs, common 

 ploughs, harrows, scarifiers, grubbers and horse-hoes, 

 rollers and clod-crushers, admit of this two-fold con- 

 sideration, and require it in order that their real 

 value or usefulness to the farmer may be fairly 

 estimated. There are a great many forms of all these 

 implements: that is the best of each, in which excel- 

 lence of work and lightness of draught are united in 

 the most profitable proportion. 



In estimating the efficiency of the different imple- 

 ments which claim our notice, we shall have to con- 

 sider the object for which they are used, and how far 

 they are respectively successful in effecting it. This 

 will be better done when we come to describe them 

 each in its turn. At present, we may make a few 

 remarks on the other subject, which we have said 

 affects machines generally — that of draught, and on 

 our present means of measuring it in farm imple- 

 ments. 



The first agricultural dynamometer, and till 

 lately, we believe, the only one in use, consisted 

 simply of an elliptic spring ; and the degree in 

 which this spring collapsed, on being pulled asunder 

 lengthwise, was taken as an index of the strain to 

 which it had been subjected. One of the sides of 

 the ellipse being fastened to a metallic plate, on which 

 the spring lies, its collapse, on subjecting it to a 

 longitudinal strain, (as, for instance, by making it a 

 link in the draught-chain of a plough,) causes the other 

 side to approach i t, and this motion is communicated 

 by means of rack-work and pinion, or by a compound 

 leverage, to a radial index on the other face of the 

 metallic plate, where a circular scale, to which this 

 index points, has been divided, by previous trials, 

 into cwts. and stones. The position of the index on 

 the scale is thus indicative of the amount of longitu- 

 dinal strain to which the spring may be subjected. 

 J* it be attached to a plough, the effort of the horses 

 in drawing the implement through the ground will 

 be exhibited by the position of this index; for 

 ^nen the strain is greatest, as where the ground 



% k*' **' Wi ^' owin o t0 tne greater collapse 

 01 the spring, point to x greater number of 



cwts. and stones as the measure of the horse's exer- 

 jwn, than when the soil being loose the implement 

 is more easily pu li e d through it. This instrument 

 nas bfim . good deal uged in determill jrig the 



draught of ploughs, but with little service, owing to 

 ,. ne extr eme variability of the strain which it is 

 Jjerc required to measure. The density of soil, as 



, P lou &a is drawn through it, is so rapidly and 

 ince Ssan t lv variable, that so far from being able to 



ran fi the avera g e draught from watching the 



*Piwy- oscillating index of this dynamometer, the 



Perator is unable to state at any one time what the 



nmT ? f the index actually is. In order to 



Cntt? y s defect in this instrument, Messrs. 



conw 5 ndHalJ en, of Winslev street, London, have 



is a fi amodincati °n ^ it, of which the following 



section^ 6 " A c y nnder and piston, represented in 



of th ' ^ here inter P ose d between the two sides 



Wort e .fP ri Pg by the same system of levers which 



is rpn i , lndex > and the motion of the piston 



with M , diffi ™lt by the cylinder being filled 



DiernJi i l ch must Pass through small holes 



^sition m a piston before the latter can shift itS 

 index ^A, slu ggishness is thus imparted to the 



accurat i ch aIlows its average position to be more 

 'nstrurne nt est l mated - Still > however, in using this 

 on his • °P erat °r has to depend a good deal 



°wn judgment in pronouncing what the 



draught of the implement under trial is ; and this is 

 an imperfection. 



Instead of attempting to destroy these oscillations, 



variability of the dr it of implements of cultiva- 

 tion, owing to the variable density of the soil. We 





Cottam's Dyxamometer.* 



much the better method is to adopt an arrangement 

 by which they may be recorded by pencil on paper, 

 in the same way as in anemometers the variable 

 force of the wind is recorded. Mr. Clyburn, 

 engineer to the Earl of Ducie's iron works at Uley, 

 Gloucestershire, has constructed an instrument on 

 this principle, which is represented as at work in the 

 subjoined figure. 



t 

 t 



i 



■ 









i 



: 



1 





• 



do not know of what ploughs these record the 

 draught, nor whether they were working at the same 

 depth in similar soils at the time; but it is evident 

 that they are far more instructive than the most 

 lengthened and detailed description, of the nature 

 and intensity of the effort which the horses made in 

 drawing the implements through the ground. 



We see that the draught of the first plough 

 averaged 4^ cwts., and that of the second not more 

 than 2J cwts. ; the draught, also, of the first plough 

 is obviously more intensely, but not more rapidly va- 

 riable than that of the second. We hope hereafter 

 to be able to lay before our readers an Essay on the 

 draught of some of our best English and 

 Scotch ploughs under similar and under vari- 

 able circumstances — written, not by ourselves, 



Clyburx's Dynamometer.! 



The spring in this case is spiral, and the strain which 

 it is intended to measure is made to compress it. 

 The motion of the plough is communicated by 

 means of the wheels, which hang from the instrument 

 and roll on the ground, to a cylinder within the case 

 of the spring, and as this revolves it unwinds and 

 rolls up a strip of paper which is wound on another 

 cylinder close by it, within the same case. This paper 

 is marked as in the following figures, with trans- 

 verse (vertical) and longitudinal (horizontal) lines, 

 the one corresponding to the positions of the dyna- 

 mometer's index, under the strains successively of 

 1, 2, 3, 4, &c. cwts., and the other dividing the 

 paper into sections of a width corresponding to 25 

 yards of ground passed over, as calculated from the 

 size of the wheels communicating the motion of the 

 plough. As already stated, when the power is applied, 

 the spring is compressed, and this gives motion to a 

 rack and pinion that has a pulley fixed on the same 

 spindle; this pulley has a chain passing round it, 

 which gives motion to a pencil and pointer; the 

 pencil oscillates in a line, parallel to the cylinders just 

 described, and it is kept by a spring pressing upon 

 that cylinder, which, as the plough proceeds, is wind- 

 ing up the strip of paper which we have been 

 describing. The consequence is, that the paper 

 carries off, marked upon it, an irregular line, the 

 position and character of which depends upon and 

 indicates the intensity and irregularity of the strain 

 to which the spring has been subjected. The curious 

 and interesting figures below are reduced (J) from 

 actual drawings by the pencil of this dynamometer 

 when attached to two different ploughs. 



nor by any other experimenter on this sub- 

 ject, but by the unerring pencil of this dyna- 

 mometer; and we are sure that a simple 

 examination of the paper of Clyburn's dyna- 

 mometer, after being applied to different 

 ploughs working at various depths in various 

 soils, will be far more interesting and in- 

 structive than a detailed description of the trial 

 by a most accurate and attentive observer. 



We hope to be able to inform our 

 readers, as we proceed, of the draught taken 



by this dynamometer of the different machines we 



describe. 





They make good our remarks as to the extreme 



* The price of this instrument is Jl- 



t Price 14/. 



GE0-AGR1CULTUR.\L NOTES ON SOUTH 



GLOUCESTERSHIRE. 



(Concluded from page 578.) 



Marls tone. — Below the sands of the inferior oolite lie 

 a series of beds which, near Dursley, where they are most 

 fully developed, consist of an indurated sand, containing 

 vast numbers of shells. This rock, which receives the 

 name of Marlstone, is generally of flight-brown colour, 

 while the shelly concretions which everywhere pervade 

 it are of a grayish blue. It is exceedingly tough, and is 

 extensively used as building material. Immediately 

 above it, and separating it from the sand of the lower 

 oolite, a very thin bed of clay occurs, containing thin 

 layers of limestone rock, precisely resembling the lias 

 limestone. It frequently is not easily traceable, from 

 being here and there obscured by overlying debris ; a 

 very excellent section of it, however, may be observed on 

 descending Frocester Hill, towards Coaley Hamlet ; after 

 passing the limestone, and then the sand of the inferior 

 oolite, we there find that they rest on this stratum, aver- 

 aging 10 or 12 feet in thickness, of a light-coloured clay, in 

 which as many as a dozen courses of a grayish limestone, 

 each not above 3 inches in thickness, occur. This bed is 

 also well seen at Tick's Hill, below Coaley Wood, and at 

 Waterleigh Valley, on the other side of Stincncombe, in 

 each of which places thin limestone beds are to be seen. 

 It is also seen at Horton Hill, where it is a dark-blue 

 clay ; and it is visible at intervals along the foot of the 

 hills between these places. The junction between the 

 marlstone and sand of the lower oolite is easily traced 

 when this bed of clay which separates them is visible. 

 This, however, is not everywhere the case, and, there- 

 fore, though at Dursley, where the character of the 'rock 

 is well developed, boundaries are easily traced, this is not 

 easily done near Bath, where its character is much 

 altered. At Dursley the marlstone forms an extensive 

 terrace, stretching out from the foot of Stinchcombe 

 Hill half a mile into the valley ; beyond VVotton-under- 

 Ed<*e, however, and in the southern part of our district 

 near Bath, it does not form so important a member of 

 the oolitic series, being thinner, and losing the indurated 

 and rocky character of the Dursley rock ; and as the bed 

 of clay above it there disappears, or is not easily trace- 

 able, it is not easy to distinguish it from the sand, which 

 there occupies so considerable a portion of the escarp- 

 ment. The section at Frocester Hill just noticed, 

 exhibits also the character of the marlstone. It there 

 consists of a series of beds of rock, of the character 

 described above, from three to thirty feet thick, alter- 

 nating with beds of blue and brown marl, varying from 

 ten to twenty feet in thickness, and comprising in all a 

 thickness of about 100 feet. Not far from this section 

 the bed of clay above the marlstone is of a dark colour, 

 which, many years since, gave rise to the idea of the 

 then proprietor of the land, that, probably, coal was not 

 far off, and trials were accordingly made. A shaft was 

 sunk, which, of course, has been long since filled up, but 

 the mound of the material excavated still remains, a 

 monument of the geological ignorance which then existed . 



