552 



MONTHLY JOURNAL OF AGRICULTURE. 



it with liquid acids, or impart to its surface elec- 

 tric sparks. Tlie retina itself, which sympathi- 

 zes with the pupil, is insensible to the influence 

 of the most active mechanical agents. Phenom- 

 ena so mysterious should teach us with what re- 

 serve we sfiould reason on analogies drawn from 

 experiments made upon inanimate substances, 

 to the far different and more difficult case of or- 

 ganized matter endowed with life. 



In conclusion, then, it appears that of all the 

 various intluences popularly supposed to be ex- 

 erted on the surface of the earth, few have any 

 foundation in fact. The precession of the equi- 

 noxes, the accumulated etiect of which rendered 

 necessary the alteration of the calendar, which 

 produced the distinction between the old and 

 new style, is a con .sequence of the moon's attrac- 

 tion combined with that of the sun upon the pro- 

 tuberant matter around the equatorial parts of 

 the earth ; and the nutation of the earth's axis, 

 and the consequent periodical change of the ob- 

 liquity of the ecliptic, is an effect due to the same 

 cause. I have on another occasion shown that 

 the tides of the ocean are real effects also 



arising from the combined attractions of the 

 moon and sun, but chiefly of the former. 



The precession of the equinoxes is a progres- 

 sive annual change in the position of those 

 points on the firmament where the center of the 

 sun crosses the Equator on the '21st of March and 

 the 21st of September. It has been ascertained 

 by observation, and verified by theory, that these 

 points move annually on the ecliptic with a slow 

 motion in a contrary direction to the apparent 

 motion of the .sun ; inconsequence of which the 

 sun, after each revolution of the ecliptic, meets 

 these ipo'mts before that revolution has been com- 

 pleted ; consequently the sun's center returns to 

 the same ecjuinoctial point before it makes one 

 complete revolution of the heavens: hence has 

 arisen the distinction between a sidereal year, 

 which is the actual time the earth takes to make 

 a complete revolution round the sun, and an equi- 

 noctial or civil year, which is the period be- 

 tween the successive returns of the center of the 

 sun to the same equinoctial point, and is the in- 

 terval within which the periodical vicissitudes 

 of the seasons are completed. 



NEW USES OF IRON . . . IRON HARROWS. 



Is few^ branches of trade or manufacture is 

 there probably greater latitude for extension 

 than in the field which lies open for new uses of 

 Iron. Every day suggests some new object for 

 w^hich it has not before been employed, and then 

 the wonder is that it was never so employed 

 before. 



In Mr. Colman's last " European Agricul- 

 ture," vol. i. part V. quoting Mr. I. Allen Ran- 

 some's treatise on the Implements of Husband- 

 ry, he says, on the subject of Harrows — '■ There 

 are several varieties of HaiTows, but, excepting 

 the frame being made of iron instead of wood, 

 and their being connected by hinges, so that 

 the frame becomes, so to speak, flexible, I see 

 no prominent excellence to be pointed out," — 

 and then quotes — " In an experiment made be- 

 tween a pair of wooden harrows and a pair of 

 iron ones, constructed on the same plan, and 

 having the same number and precisely the same 

 disposition of the teeth and frames, although 

 those of iron were found to be twenty pounds 

 lighter than those of wood, yet the former 

 worked decidedly better and steadier than the 

 latter. In fact, the iron hartows cut into the 

 land, while those made of wood rode, or rather 

 danced, upon the surface." We confess we do 

 not well see how this could be. If the wooden 

 frame were heavier, why should the teeth not 

 sink as deep ? In respect of the hhig-es con- 

 necting the harrows and making them flexible, 



~(1]40) 



BO as to accommodate their action to uneven 

 surfaces, we have long had such harrows. In 

 fact, our implement makers have all the best 

 kinds, v*'e are inclined to think, of that imple- 

 ment. Their own interest and public spirit, we 

 trust, will prompt them to import samples, at 

 least, of whatever is said or supposed to be su- 

 perior in its kind. Their patrons have a right 

 to judge for them.selves ; and we presume there 

 will be few machines or implements adapted to 

 our country that may not be seen in factories eo 

 immense as Ruggles and Moore's. 

 A late English paper says: 



" The use of iron is still greatly extending in 

 Manchester, where the principles of its applica- 

 tion are well understood, and all the casting e.s- 

 tablishmcnts are in active operation. The most 

 novel application of this material is in the Inde- 

 pendent Chapel erecting in Salford, near the 

 Broughton Bridire, from the designs of Mr. 

 Richard Lane. The roof is framed of cast iron 

 principals, curved, and meeting at the top in a 

 Gothic arch. Each half is in two pieces, finnly 

 bolted together, and the principals are connect- 

 ed by tie-rods. The feet of the principals are 

 spread out, and rest on blocks of stone, but are 

 farther supported by iron columns, built into the 

 wall, which stand upon stone corbels at the 

 ground level. There are shoes, cast on the prin- 

 cipal!?, to receive the purlins. There will be a 

 schoolroom underneath. There are two bights 

 of iron columns, the upper supporting the iron 

 girders for the galleries. These girders are 

 curved in form, so as to approach nearer to the 

 section of the steps of the galleries." 



