94 



THE CIVIL ENGINEER AND ARCHITECTS JOURNAL. 



[Feb. 24, 



wovks of Sir Stamford Raffles. There seemed to h.m some h.ng l.ke an 

 analogy m the huildings.-Mr. Catherwood sa,d he had ""' """^'^'^ f-f J' 

 Tite a. led whether he had examined the masonry "''\'-^f«;f . ° '.'''..r^f. '" 

 which it is formed, and whether it is so executed as to indu.e the 1 ehef that 

 tTe To tecs were a cultivated people. He also inquired w^hether they were 

 acQuainted with the working of metal, as for instance, had arty idols of 

 bro ze h en found, as in Egypt and elsewhere.-Mr. Catherwood said dee- 

 dedlv that the masonrv was regular and well executed. All that .s known 

 with" reaard to their power of working metal, was the testimony to i ad- 

 duced hv the historians of the early conquests of Cortes and otiiers. 

 There had also been found raanv beautiful objects, some of gold, some ot 

 silver hut mostly of copper. Their proficiency in tlie arts was also i lus- 

 trated by the delicate paintings on their MSS., some of which he had in- 

 tended to have brought with him, but being on a kind of bark, they were so 

 fragile as to be liable to iniurv.— Mr. Tite said he had some wood engravings 

 of °them in the well-known work Purchm's Pilr/rim.—m. Poynter, in re- 

 ference to the analogies discoverable in the ornaments, cited a case ot 

 the pectdiar Greek scroll, which is an emblem of water, being foriiied on a 

 Penivian vase, where it evidently had the same meaning, the fish being re- 

 presented underneath it, as it is sometimes found in the Greek.— Mr. Donald- 

 son inquired if any windows were found in the Toltecan buildings.— Mr. 

 Catherwood said none, only doors. The doors in some of the large bmldings 

 were very ornamental. That at Chichon Itza was highly decorated.— Mr. 

 Donaldson asked if there were any bed-mouldings to their coriiices.— Air. 

 Catherwood said none. In answer to another inquiry, he said the material 

 of the buildings he had seen was limestone, there had been none of sand- 

 stone or granite seen by him, and he was disinclined to believe there were 

 anv It was said that the great sacrificial stone in the city of Mexico was 

 of granite, hut he had not examined it. It is very generally supposed that 

 the Egvptian buildings are of granite, but he had been much surprised after 

 two yeirs residence in the country, to find that with the exception of one or 

 two small buildhigs, they were all of grey sandstone, lie said that no 

 cramps had been found among the masonry, and that the material of the 

 beam^ of the doors was sapote wood, on which the carving is very sharp and 

 beautiful Mr. Stephens had got two beams away, but they were afterwards 

 destroyed by fire. Mr. Donaldson asked whether the wood was used as an 

 object of rarity, or because thev had not stones long enough to cover the 

 entrances —Mr. Catherwood said the wood was used purely as an object of 

 luxury, as it admitted of richer car\ing.— Mr. Poynter asked if any quarries 

 had been found.— Mr. Catherwood replied none, nor tombs. This was a 

 matter of deep regret, for such a discovery would have been highly inter- 

 esting They heard of many campos santos, but in only one instance did 

 they find a burial ground, when they obtained a skull, which had been exa- 

 mined by Dr. Morion of Philadelphia, who had pronounced it exceedingly 

 curious —Thanks were then voted by acclamation to Mr. Catherwood. We 

 should observe that around the room were arranged a number of drawings 

 by Mr. Catherwood, which excited much attention, from their remarkable 

 union of architectural precision with pictorial effect. 



The discussion upon the vahies nf pumps was also resumed. The resem- 

 blance between the disc valve of Palmer and Perkins, and that invented by 

 Belidor was examined, and the general opinion appeared to be that Messrs. 

 Palmer and Perkins' valve would he found very useful in large pumps for 

 mines, through which much sand or chi|)S passed. The general question of 

 valves with large openings with their inlluence on the working of the deep 

 mines of Cornwall and otlier places was noticed. 



The discussion occupieil so much time that no papers conld be read; 

 those, therefore, which had been appointed for the 20th, were announced for 

 reading on the 27th instant. 



INSTITUTION OF CIVIL ENGINEERS. 



\Feb. 20. — The President in the Chair. 



The discussion on the screw propeller, which was carried to so great a 

 length at the last meeting, was resumed. Mr. Grantham explained the con- 

 struction of the propeller used on board the Liverpool Screw. It was formed 

 of four arms. 



Mr. Grantham being present, stated that he had come prepared to answer 

 a Question which had been put at the last meeting respecting the angle at 

 which the blades were set. The mean angle of the blade, taken in the line 

 of the radius, was 45°, and this liad given a most admirable result. The par- 

 ticular object of his paper had been to prove, by the data obtained in the 

 experiments on the Liverpool Serein, that it was both practicable and desi- 

 rable to construct the wheel of such a large diameter and long pitch, that 

 its motion would be comparatively slow, so much so, as to admit of its being 

 driven direct from the engines similar to the ordinary paddle wheels, and to 

 use the condensing engine. He stated that he most approved of the form 

 of screw adopted by Mr. Ericsson with the expanding pitch. He objected 

 to the form exhibited in some of the models laid on the table ; propellers 

 thus constructed could not conveniently be made to present a large surface 

 to the water, without which a considerable slip would take place and a con- 

 sequent loss of effect. It also formed an additional obstacle to direct action. 

 Mr. E. Galloway contended that the amount of slip was greater than was 

 imagined owing to the following current at the stern. He also argued that 

 there was no advantage to be gained by the expanding pitch. Mr. Cowper 

 related some experiments made on a small toy, (with blades in the form of a 

 screw propeller,) which is projected into the air, by having a rapid rotary 

 motion communicated to it— form these he was to give a decided pre- 

 ference to the expanding pitch. Mr. Braithwaite confirmed Mr. Grantham s 

 statement regarding Bcrisson's propeller, and promised at a future meeting 

 to give the results obtained on board the Prirtceton steamer, U. S. America. 



ELECTRO-MAGNETIC MOTIVE POWER. 



At the Roval Institution, on February 9th, W. R. Grove, Esq., gave a 

 lecture " On the Progress made in the Application of Electricity an a Mo- 

 tive Power." 



The subjects of Mr. Grove's communication were, 1, a brief summary of 

 the laws of the electro-magnetic force ; 2, a description of the chief modifi- 

 cations of the engines to which that force has hitherto heen applied ) 3, the 

 commercial statistics of its application ; 4, the purposes for which this power 

 is available. In dealing with the first of these stdijects, Mr. Grove exhibited, 

 by many illustrative and successful experiments, the well-known re-actions 

 of iron and other metals on each other, when exposed to the influence of an 

 electric current. The actual application of these familiar phenomena was 

 then shown in the working models of several machines, which were set in 

 action by the nitric acid (or Grove's) battery, invented hy Mr. Grove, and 

 described by him four years ago at the Uoyal Institution. These machines 

 may be divided into three classes ; first, those acting by the immediate de- 

 flecting force, as shown in the galvanometre, Barlow's wheel, &c. ; secondly, 

 those on what is called the suspension principle. In these, two powerful 

 electro-magnets are fixed contiguous to the periphery of a wheel, and in the 

 line of its diameter, plates of soft iron being fastened on this periphery at 

 short and equal intervals. The electro-raagnets are so arranged as to lose 

 their attractive power as soon as they have drawn through a given space each " 

 plate of iron, necessarily presented to them by the revolution of the wheel, 

 but are immediatly re-invested with this power, in order to operate on the 

 next plate. By these means the wheel is kept in constant rotation on its 

 axis. The remaining class of electrically-driven machines are applications 

 of the principle of Ritchie's reiolving magnet. In these, an electro-magnet, 

 balanced on a pivot, so as to rotate in a horizontal plane, is arranged between 

 the poles of a permanent magnet. Hence, the alternate attractions of the 

 opposite magnetic poles, combined with its own momentum, cause the 

 electro-magnet to continue rapidly revolving. Having noticed machines, on 

 these various principles, hv H. Fox Talbot, Esq., Mr. Hill, of Swansea, and 

 Professor Wheatstone, Mr. Grove proceeded to his third subject, the com- 

 mercial statistics of electro-magnetic power. It appears by the experiments 

 of Dr. Botto, that the consumption of 451b. of zinc will produce an effect 

 equivalent to a single- horse power for 24 hours. The cost of the zinc metal, 

 at 3rf. the pound, would amount toll*. 3rf. .\bout 50Jlb. of the nitric 

 acid of commerce would be required to dissolve the metal in the most econ- 

 omical and effective manner. The charge of this, at (>d. the pound, would 

 be \l. 5s. 3rf. The whole expense, therefore, of obtaining the effect of a 

 one-horse power by an electro-motive apparatus, would be \l. Us. 6(7. In 

 this calculation the cost of the requisite sulphuric acid is assumed to be 

 fuUv covered by the value of the salts of zinc produced in the operation. 

 The same amount of power produced by a steam engine would not cost more 

 than a few shillings. Mr. Grove explained that this comparitive costliness of 

 the electro-magnetic machines resulted from the sources of their force, zinc 

 and acid being manufactured, and consequently costly articles; whereas, 

 coal and water, the elements of the steam engine's force, were raw materials, 

 supplied at once from the earth. Mr. Grove took this occasion to observe, 

 that the experiments of Botto, just alluded to, were made with his (Grove s) 

 battery ■ and that upon the cost of the constituents of this, the calculatmns 

 were founded. At first sight, this battery would appear a dear form, from 

 the expen'ie of the nitric acid ; but a little consideration proves the contrary 

 of this Compare it, for example, with a battery merely charged with dilute 

 sulphuric acid (the cheapest possible electrolyte), to perform an equivalent of 

 work, (as the decomposition of a given quantity of water,) a series of three 

 cells of the ordinary battery is necessary ; hence the consumption of three 

 equivalents of zinc, and tiiree of sulphuric acid. But the intensity of the 

 Grove's battery is such, that the same resistance can be overcome by one 

 cell consuming only one equivalent of zinc, one of sulphuric acid, and one- 

 third of nitric (there being in this acid three available equivalents of oxygen.) 

 Independently of this smaller consumption, Grove's battery has the advan- 

 tage of occupying only i^ih of the space of the other constructions. In con- 

 chiding his communication, Mr. Grove mentioned the two well-known appb- 

 cations of electric power— the electric telegraph and the electric clock. To 

 neither of these can steam, or, indeed, any known force, be so apphcable as 

 that which travels with a greater velocity than light itself. 



