1844.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



199 



accompanying engravings, which show a longitudinal and transverse section 

 of a box for suiHiorting the ends of the axle; fig. 1, is the longitudinal 

 section of the apparatus, and fig. 2, a transverse section drawn on a 

 smaller scale ; in fig. 1 a, is a portion of a railway axle, thai part from 

 a to b, being reduced in thickness; c, c, are two" circular rings or carriers, 

 which are made to slip over the axle a, b, and fit loosely thereon, these rings 

 or carriers are connected together by means of four;, pins d, rf,>'hich form 

 axles to the rollers c, e ; these rollers are bevelled oflf at each end and made 

 to fit against corresponding bevelled parts as"will be clearly seen, thereby 

 preventing the axle a, b, moving endways. The carrier c, c, and rollers e, c, 

 being put together are in the first place slipped into the box g, g, the rollers 

 together with the box are then slipped over or upon the axle a, h, and secured 

 by the nuts h, and end plate i. The axle being put in motion, the rollers e, e, 

 besidi'S having a rotary motioniwill be carried, together with the carrier plates 

 c, c, round the main axes a, b. 



The inventor claims the application of friction rollers or wheels to axles, 

 such rollers having rounded or bevelled ends, and mounted or supported by 

 carrier plates, which fit loosely upon the axle and revolve round the axle as 

 well as the rollers, some being kept together by means of caps, screws, or 

 other contrivance. 



IMPROVEMENTS IN THE MANUFACTUEE OF ZINC. 

 James Graham, of Wapping, Middlesex, for ' Improvements in the construc- 

 tion of pots and vessels, and furnaces used in the manufacture of zinc, and in other 

 manufactures, and also improvements in the treatment of the ores of zinc, in the 

 process nf manufacturing zmc."— Granted October 18, 1843 j Enrolled April 

 18, 1844, reported in the Mechanics' Magazine. 



1. The improvement in the construction of pots and vessels. The mould 

 for the external surface is composed of a number of staves bound together 

 with hoops, which, instead of being rivetted together at the two ends are 

 joined by screws, whereby they are readily slackened to allow the staves to 



e withdrawn when the vessel has been formed inside. This mould is dropped 

 upon a core placed in an upright position, which regulates the internal form 

 and thickness of the pot or other vessel ; the core being secured at the base 

 by means of stays, leaving an open space all round, into which the composi- 

 tion for the formation of the pot is rammed by a tool made for the purpose. 

 In the top of the pop, as thus moulded, but which subsequently becomes the 

 bottom, tl'.ere is an aperture left which serves to receive a pipe to convey off 

 the metal into the receivers in the manner next described. 



2. The imiiroveraents in furnaces. Each furnace consists of an arched oven, 

 jn which a number of the pots or crucibles before described are set ; the flues 

 being so arranged, that the action of the fire may come into play all round 

 their external surfaces. Every pot has a pipe perforated throughout its whole 

 length with small holes, inserted into the^hole in the"bottom of the same, and 

 standing up on the inside to nearly the same.height with the sides , through 

 these small holes the vapour of the metal, as it is driven off by the heat, 

 escapes, and is conveyed downwards by means of another pipe attached to 

 the bottom of the pot on the outside, into receivers placed in a chamber 

 formed below the furnace, where it is collected as condensed. The vapour 

 cannot ascend as the pots are furnished with lids, which are securely luted on 

 after the charge has been put in. 



3. The improvements in the treatment of the ores in zinc. The products 

 arising from the distillation of the ores of zinc are retained by another set of 

 pipes leading from the bottom of the pots. When blende is distilled, the 

 sulphuric acid is collected in chambers, such as are commonly used in the 

 manufacture of that acid ; and when calamine is being reduced, the carbonic- 

 acid gas may be collected for any of the purposes to which it is applied. 



ELECTRO-MAGNETIC MOTIVE POWER. 



Lectures on Electricity. By Henry M. Noad. Loudon : George Knight 

 & Sons, 1844. 



(.Second Notice. J 

 On the previous occasion, in advertmg to this useful work, we availed our- 

 selves of some of its more general features, we shall now refer to tliat part 

 wdiich is particularly interesting to our readers, the application of the electro- 

 magnetic sciences to mechanical purposes. The connection of electricity and 

 magnetism, on the phenomena of which the practical applications are based, 

 hail been long suspected ; the German philosophers in particular, devoted 

 their attention to this subject, though in the last century great diversity of 

 opinion jjrevailed. In a memorable discussion, promoted by the oifering of a 

 prize on the part of the Electoral Academy of Bavaria, it was maintained by 

 Professor Van .'^winden that the resemblance between the operations of elec- 

 tricity and magnetism was apparent only, and had no real basis. He conse- 

 quently considered the power of each was distinct in its nature. Pro- 



fessors Steigelehner and Hiibner took the opposite side, and contended for the 

 doctrine now received, that both sets of phenomena are derived from the same 

 cause. It was not, however, until 1819 that this ijuestion was set at rest by 

 Professor Oersted, of Copenhagen, to whose important discovery we have 

 since been so much indebted. 



" The fact observed by Oersted was, that when a magnetic needle was 

 brought near the connecting medium, (whether a metallic wire, or charcoal» 

 or even saline fluids, of a closed voltaic circle,) it was immediately dellected 

 from its natural position, and took up a new one, depending on the relative 

 positions of the needle and wire. If the connecting medium was placed hori- 

 zontally over the needle, that pole of the latter which was nearest to the «c- 

 gative end of the battery, always moved ivestivard ; if it was placed under, the 

 same pole moved to the east. If the connecting wire was placed parallel with 

 the needle, that is, brought into the same horizontal plane in which the needle 

 was moving, then no motion of the needle in that plane took place, but a 

 tendency was exhibited in it, to move in a vertical circle, the pole nearest the 

 negative side of the battery being depressed when the wire was to the laest of 

 it, and elevated when it was placed on the eastern side. Fig. 2 represents 

 Fig.l. Fig. 2. 



Fig. 3. 



a convenient arrangement 'for exhibiting the action of a wire conducting a 

 current of Electricity on the magnetic needle, a a, two turned wooden pil- 

 lars screwed into a base board B, and surmounted by two mercury cups c c. 

 n, a copper wire, the ends of which dip into the mercury, as do also the wires 

 connected with the opposite extremities of a simple voltaic battery. A cur- 

 rent of Electricity can thus be made to pass either way along the wire D : c is 

 the magnetic needle nicely poised on a wire, which by the screw G may be 

 elevated or depressed, and the needle thus set either above or below the wire 

 D, or it may be removed and replaced by the dipping needle 6 fig. 1. As in all 

 electro-magnetic researches, it is necessary to bear in mind these affections of 

 the needle and electrified wire ; several contrivances have been made to assist 

 the memory respecting the details. Fig. 3 , represents the plan of Dr. Roget. 

 .1 BSsa. slip of card, on each side of 

 which, a line rt 4 is drawn along the 

 middle of its length, the end n being 

 marked + , the end b — , and the cen- 

 tre c being crossed by an arrow, at 

 right angles to it, directed as in the 

 figure. Through the centre, and at 

 right angles to the plane of the slip of 

 card, there is made to pass, a slender 

 stem of wood, [at the two ends of 

 which, are fixed in planes, parallel to 

 the slip of card A B, the circular 

 discs of card marked respectively 

 with the letters N and S, and with 

 arrows parallel to, but pointing in a 

 contrary direction to the one at c. 

 Tlie same marks must be put on the 

 reverse of each of the three pieces of 

 card, so that when held in different situations they may be seen without 

 turning the instrument. 



"If the line a b, be supposed to represent the connecting wire, (the direction 

 of the current of Electricity being denoted by the signs + and — at the ends 

 of the line) the arrow at the centre will point out the direction in which it 

 tends to move, when under the influence of the north pole of a magnet, 

 situated at N ; or of a south pole situated on the other side, as at S; and 

 vice versa the arrows JVand S, will indicate the directions in which the north 

 and south pole respectively tend to revolve round the connecting wire in its 

 vicinity, with relation lo the direction of the current of Pilectricity, that is 

 pa^ ing through it. It must be observed that the poles N, S, are not consi- 

 de d as in connection with each other, or as forming parts of one magnet ; 

 th r operations are exhibited singly and quite independently of each other- 

 T c advantaj^e of the instrument consists in its being capable of being held in 

 any situation, and thus easily adapted to the circumstances of any fact or 



peijmtnt ol which we may wisli to examine the theory," 



