18 54. J 



ON M. DAVY'S NEW ELECTKO-MAGNETIC-ENGINE. 



83 



Secondly, we have a climate more equable, perhaps, than that 

 of any other country in Europe, of which one of our monarchs 

 remarked, that there are more hours in the day in which a 

 man may enjoy himself out of doors in this country than in 

 any other country in Europe. But is that all ? It gives us a 

 constant industry ; it gives the means of workiug from early 

 morn till night during the whole year. These are some of our 

 natural advantages. It allows out-of-door work to go on con- 

 tinually. What have we besides ? ' We have vast mineral 

 wealth, greater than the gold of California or Australia — mines 

 of iron and coal — short words, but having a wide and extended 

 meaning. Iron means arms and ploughshares, tools and 

 engines, bridges and aqueducts. It means those vast bridges 

 that span the 3Ienai Straits, one of which now stands the 

 monument of the genius of one who is an ornament to this or 

 any other country — I mean Mr. Stephenson — and it means, 

 moreover, railways, which are now the highways for the whole 

 world. These are some of our natural advantages. But have 

 we not more ? In that short word "coal," besides the fire 

 which gives comfort in our dwelling, it is the foundation of 

 our great hardware manufactures; it moves by steam all our 

 factories ; it gives employment to myriads of women and 

 children — the tender sex and the tenderest age ; it moves all 

 our trains ; it moves half our vessels. Coal and iron together 

 mean a moving power equal to millions of pairs of hands, 

 requiring neither clothing nor food to maintain them. The 

 coal which is obtained in Great Britain alone amounts to 

 thirty-seven millions of tons annually, whilst the produce of all 

 Europe amounts to only seventeen millions of tons — not half 

 what is raised in this island. Now what are our acquired 

 advantages ? They are still greater than our natural advan- 

 tages. First of all, after a century of struggle, we get our 

 religious freedom by the Keformation of 1530, and after a 

 century of contest we had our civil freedom established by the 

 Kevolution of 1688. This country has afforded an asylum to 

 foreigners from intolerance and bigotry in other countries, 

 which has been repaid by a hundred inventions and discoveries. 

 Our freedom was won, as Burke says, by our ancestors, owing 

 to their spirit in the hour of contest, and their tenderness in 

 the triumph of victory. Freedom is the mother of many 

 blessings — of order and security, of industry, and enterprise, 

 of wealth and plenty. Now, let us look for a moment at the 

 effects of these natural and acquired advantages combined 

 with the forty years' peace we have till recently enjoyed. 

 Look at the changes they have produced, calling for corres- 

 ponding alterations in the laws and corresponding facilities 

 in our commercial transactions. But I have spoken of our 

 social regulations as the third cause of the greatness, safety, 

 and happiness of this country. What has tlie change been ? 

 First, in the population. In 1780 our rural population was to 

 the civic population as 2 to 1 ■y'^novf the proportions are exactly 

 reversed, and the population of our cities and towns employed 

 in manufactures and commerce are as 2 to 1 of those employed 

 in agriculture. From the census of 1801 you will find there 

 has been a general increase of the population of 15 per cent — 

 in the rural population of 10 per cent., and in our cities of BO 

 per cent. — that is, those who possess personal property in our 

 cities have increased threefold as compared with the other 

 portion of the population. — (Jonr. Socicti/ ArU.) 



On M. Marie-Davy's New Electro-Magnetic Engine. 



BY M. BECQUEREL. 



Attempts have been made for the last 20 years, to construct 



machines in which the magnetic property imparted to soft iron 

 by the electric current should be employed as a motive power; 

 but the electro-motive machines hitherto brought fonvard have 

 been far from presenting any economical advantages over 

 steam-engines. 



Any electro-magnetic engine must be composed cs.sentially 

 of a series of electro-magnets of soft iron, of armatures also of 

 soft iron, or arranged as electro-magnets, with various adjuncts, 

 for the transmission of the electricity furnished by a battery or 

 electro-magnetic machine, and of a commutator or breaker, for 

 the purpose of producing a continuous circular or backward 

 and forward motion. 



In the machines hitherto constructed, these various parts do 

 not combine all the conditions desirable for making u.se of all 

 the power set in action ; a cheap, constant, and powerful source 

 of electricity does not yet exist ; the soft iron, never being 

 pure or perfectly malleable, retains for a longer or shorter 

 period after each interruption a portion of the magnetization 

 which had been communicated to it by the current ; the pri- 

 mitive current and the extra current produce contrarj- effects, 

 causing a mutual injury ; and the commutators often present 

 alterations when the circuit is closed. 



M. Jacobi, moreover, who has carefully studied the subject 

 of the practical employment of electro-magnetic engines, has 

 arrived at this result — that the mechanical effect or amount of 

 work, considering the expenses necessary to keep them in action, 

 is far inferior to that of the other motive powers in use. But 

 this does not set the question at rest ; for if we succeed in dis- 

 covering sources of electricity more economical and powerful 

 than those at present in use, and in avoiding a portion of the 

 inconveniences already mentioned, electricity and magnetism 

 may take their place with heat as motive forces. 



These considerations show that all researches having for 

 their object the removal of some of the diiSculties encountered 

 in the employment of electricity as a motive power, should be 

 received favourably; and the memoir recently presented by M. 

 Marie Davy to the Academy contains some new views worthy 

 of attention, as will be seen from the following report. 



M. Marie thought, and with reason, that in order to obtain 

 the maximum of effect in electro-magnetic engines, the electro- 

 magnets and the armatures must act up to the point of contact, 

 seeing that the electro-magnetic force, as he found by calculii- 

 tion and experiment, decreases so rapidly with the distance, 

 that in emploj-ing two electro-magnets, when these are brought 

 together from a distance to the point of contact, they developc 

 an amount of work in such a manner that five-sixths are pro- 

 duced in the last millimetre, and the half of the remainder in 

 the last but one ; when the second electro-magnet is replaced 

 by an armature of soft iron, three-fourths of the quantity of 

 work are produced in the last millimetre through which the 

 armature passes, and more than half the remainder in the last 

 but one. In most of the rotatory electro-magnetic machines 

 hitherto constructed, the moveal;ile armatures pass rapidly before 

 the fixed electro-magnets, following a line perpendicular to the 

 axis, without coming into contact ; thus the entire amount of 

 work that might be obtained is not uindo use of. Wo must, 

 however, refer to the fact that Mr. Froment, who has paid 

 much attention to the electro-magnetic motor appanitus, has 

 constructed a machine in which an interior wheel, furnished 

 with armatures of soft iron, revolves upon thctorniimil faces of 

 the fixed electro-nuignets, so as to make use of the magnetic 

 attraction even up to the point of contact of the mnguctizcd 



