202 MANURE 



back-wards and forwards over the linen spread upon a polished table underneath, 

 render it smooth and level. The moving wheel, being furnished with teeth upon both 

 surfaces of its periphery, and having ii notch cut out at one part, allows a pinion, 

 uniformly driven iu one direction, to act alternately upon its outside and inside, so 

 as to cause the reciprocating motion of the chest. This elegant and much-admired 

 English invention, called the mangle- wheel, has been introduced with great advantage 

 into the machinery of the textile manufactures. 



Mr. Warcup, of Dartford, obtained a patent several years ago for a mangle 

 in which the linen, being rolled round a cylinder revolving in stationary bearings, 

 is pressed downwards by heavy weights hung upon its axes, against a curved 

 bed, made to slide to and fro, or traverse from right to left, and left to right, 

 alternately. 



Mr. Hubie, of York, patented in June 1832 another form of mangle, consisting 

 of three rollers placed one above another in a vertical frame, the axle of the upper 

 roller being pressed downwards by a powerful spring. The articles intended to 

 be smoothed are introduced into the machine by passing them under the middle 

 roller, which is made to revolve by means of a fly-wheel ; the pinion upon whose 

 axis works in a large toothed wheel fixed in the shaft of the same roller. The 

 linen, &c. is lapped, as usual, in protecting cloths. This machine is merely a small 

 CALENDER. 



MANGROVE. Several tropical trees yield woods to which this name has 

 been applied. Colonel G. A. Lloyd informs us, that 'the timbers are very much 

 valued for ship-building ; and a large quantity comes from Crab Island and Porto 

 Rico.' Most of the mangroves belong to the Rhieophoracece, 



MANILIiA. One of the hemps, derived from the Musa textilis. See HKMP. 



MANIOC is the Indian name of the nutritious matter of the shrub Jatropfia 

 Manifiot, from which cassava and tapioca are made in the West Indies. See CASSAVA ; 

 TAPIOCA. 



IMC ANITA is the concrete saccharine juice of the Fraximts ornus, a tree much 

 cultivated in Sicily and Calabria. It is now little used, and that only in medi- 

 cine. 



MANNHEIM GOIiI>. A brass, containing 80 per cent, of copper and 20 per 

 cent, of zinc. 



MANURE. Under the auspices of the British Association, Professor Liebig, in the 

 year 1840, first promulgated his views on agriculture, from which date we may trace a 

 spirit of investigation into it, such as had not previously existed in this country. Among 

 other labourers in this field, we must state that Mr. J. B. Lawes, of Rothamstead in 

 Hertfordshire, was occupied several years prior to the first edition of Professor Liebig's 

 work, in investigating the action of different chemical combinations when applied as 

 manures to the more important crops of the farm ; and having ever since continued 

 his experimental researches with all the lights of science with which he is familiar, 

 aided by Dr. J. H. Gilbert, a skilful analytical chemist, he has been able to arrive at 

 conclusions of greater value and precision than the merely theoretical determinations 

 of the German Professor. In the course of this inquiry, the whole tenor of the 

 results of Messrs. Lawes and Gilbert, and also of information derived from intelligent 

 agricultural friends, upon every variety of laud in Great Britain, has forced upon 

 them opinions different from those of Professor Liebig, on some important points ; 

 and more especially, in relation to his so-called ' mineral theory,' which is embodied 

 in the following sentence, to be found at page 211 of the third edition of his work on 

 Agricultural Chemistry, where he says ' the crops on a field diminish or increase 

 in exact proportion to the diminution or increase of the mineral substances conveyed 

 to it iu manure.' 



Of the vast importance, both in a scientific and practical point of view, of correct 

 ideas on the subject here at issue, a judgment may be formed from the manner in 

 which Liebig himself speaks of the mineral theory in this edition of his 'Letters on 

 Chemistry.' Thus he says of the agriculturists of England, that 'pooner or latter 

 they must see that in the so-called mineral theory, in its development and ultimate 

 perfection, lies the whole future of agriculture.' Messrs, Lawes and Gilbert published 

 the following paper in reply to Liebig. It is of so important a nature that, acting 

 On the advice of the best authority in this country, it has been retained : 



'Looking upon the subject in a chemical point of view only, it would seem that an 

 analysis of the soil upon which crops were to be experimentally grown, as well as 

 a knowledge of the composition of the crop, should be the first points ascertained, with 

 the view of deciding in what constituents the soil was deficient ; and, at the commence 

 ment of our more systematic course of field experiments, the importance of those points 

 was carefully considered. When we reflect, however, that an acre of soil six indies 

 deep may be computed to weigh about 1, 344,000 Ibs. (though the roots of plants take a 



