several sciences, including physics and chemistry; and therefore the employments connected with it, and the technical education relating to it, also necessarily include a knowledge and an explanation of the chief laws and principles of those sciences: for example, the manufacture and working in metals requires a knowledge of the sciences of mechanics, heat, and chemistry; the occupation of electro-plating necessitates a knowledge of electricity and chemistry. the numerous employments involving the construction or use of tools and machinery require a knowledge of the science of mechanics, and in some cases also of heat and chemistry.

The fundamental laws and principles of any particular science operate in a similar manner in all trades, and are substantially the same for all learners: for example, the same chemical and electric principles operate in the galvanic batteries of telegraphists and electro-platers, as in those of the scientific investigator; the laws of combustion are the same in a puddler's furnace as in a domestic fireplace; water boils at the same temperature, whether it be in a chemist's flask, a brewer's copper, or in a servant's saucepan; the laws and principles of science, therefore, cannot be readily subdivided to suit particular trades. With the practical illustrations, however, the case is different; they may be selected from particular occupations, manufactures, arts, processes, and substances, so as to make the lessons suitable for different classes of persons, and thus by varying the kind of illustrations the lessons may be adapted to persons of different occupations, to agriculturists, metallurgists, and others. In courses of lessons or lectures on technology, the teacher should be very careful to select as many of the illustrations as possible from the actual working experience involved in the particular trades or occupations of his audience, and in this way the highest science may be united to the meanest art. A difficulty connected with the carrying out of this plan is, technical processes are rarely well understood by professional teachers, because those processes depend so much upon practical details.

The technological teacher must know both the science of the manufacture and the details of the manufacture itself to which that science is applied; he must be able to combine theory and practice, and continually to show the relation of abstract laws and principles to technical results. He must not only know how difficult things are done, but he must also to some extent be able to do them, and thus to teach by example as well as by precept. His teaching must be full of practical applications and familiar illustrations. Such teachers are as yet almost unknown, and Faraday, in his evidence already referred to, stated that the class of men suitable for teaching science remained to be created.

This statement made by Faraday still remains true. Our Universities have not yet supplied many schools with teachers eminent

in physics or chemistry. The sudden public demand for some indefinitely understood scientific education has produced a supply of comparatively unqualified teachers, and those appointed in some of our schools have had only a book-knowledge of the subject, but little experience in making experiments, much less acquaintance with the relations of science to manufactures, and entirely without experience in original experimental research. The ignorance of some of the simplest practical scientific matters, shown by some of these otherwise educated gentlemen, has been quite astonishing, and the most charitable supposition is that they are unaware of their ignorance.

The kind of teachers required for communicating scientific instruction are not men possessed only of a book-knowledge of science, and the power of communicating it, nor even of men who have also repeated the experiments of others as described in books, but men who, in addition to all this, are familiar with the details of manufacturing operations, and have also had considerable experience in original experimental research, and thereby acquired the power of distinguishing truth from error in matters of science, a quality of the highest value in teaching, and which cannot be acquired in any other way.

VIII. ATMOSPHERIC ELECTRICITY AND RECENT
PHENOMENA OF REFRACTION.
By SAMUEL BArber.

WHATEVER Connection may exist between earthquakes and electrical disturbance of the atmosphere-a connection remarkably substantiated during the past year-there seems little reason to doubt that there exists between the electric waves or currents and the condition of atmospheric vapour a close relation. The more we examine the various changes of cloud and mist, their multiform shapes and ever-varying tints, their changes in density, altitude, and attractive or repulsive power, the more are we convinced that a force of incalculable power and undefined extent, more subtle and scarcely less potent than that of gravitation is in constant operation upon them.

The operation to which I allude, that of electricity, both atmospheric and terrestrial, seems rather to have been studied in its exceptional manifestations, than as a force subject to law, and of vast and constant, though unobtrusive, influence. The difficulty of rendering this science deductive, in its relation to meteorology, is apparent; the collection of data and the progress of experimental research form our present basis.

VOL. VII.

R

Till something more is known, however, and known more definitely, as to the nature of cloud and fog constituents, we can scarcely expect much progress in this department; and I would commend the subject to aëronauts and microscopists. Mr. Proctor, in an interesting paper on the subject of rain,* quotes De Saussure, Kamptz, &c., against Sir J. Herschel and Tyndall, appearing to incline to the views of the latter writers. He does not, however, allude to electrical action in enumerating the causes of rain. Yet it seems to me there is no reason to believe that the aggregation or dissociation of clouds and the condensation of their particles is greatly due to the influence of this force. That the movements of cloud and mist are accompanied by strong electrical action has been shown by the experiments of Mr. Crosse, of Bromfield, and Mr. Ronalds;† and it is but reasonable to think that this action may have great influence on contiguous vapour, though unaccompanied by a disruptive discharge, or any luminous appearance. My observations induce me to think that electricity is also indirectly the cause of those peculiarities of refraction which depend upon the molecular condition of the vapour media through which the light passes, viz.-Halos, Parhelia, Paraselenæ, &c.; and I may here remark that these phenomena appear to have been unusually abundant during the past year, which has also afforded such exceptional displays of aurora, &c.

On the 21st September, a halo, of large diameter, say 60°, corresponded in position with the cirrhus clouds which formed the refracting medium. This halo followed the irregularities of the cloud to a considerable extent. Its disappearance was almost instantaneous, being caused apparently by the approach of a large mass of cumulus in the lower region of the sky. Almost as soon as the latter touched the lower part of the circle, the halo vanished. The irregularities in the circle of light at one time took the form of a series of separate arcs, which bent inwards, and appeared to be composed of half-dissolved cirrhus. These irregularities of form were also very conspicuous in a remarkable halo which was seen on Friday evening, December 19th. This assumed a spheroidal form, and was intersected by streaks of cirrhus, which changed their form rapidly, and showed a prismatic refraction like that of the halo itself. The vanishing of the first-mentioned halo was perhaps caused by an alteration in the constitution of its crystals or vesicles resulting from the electric action of the cloud below.

The next appearance I have to describe was of a singularly beautiful form and perfect definition. It appeared imbedded in a mass of homogeneous vapour, and consisted of two distinct rings, the inner one of a deep cobalt blue. This ring was distant from *Intellectual Observer,' December, 1867. + Vide Sir S. Harris's Electricity.'

the moon's disc about three diameters. Its outline was clearly defined, especially towards the inner part of the circle, and the colour was exquisite in tone. Farther from the moon, by about two apparent diameters, there was another ring, less defined and wider than the first, and of a beautiful crimson colour. Altogether this was the most beautiful appearance of the kind that I ever witnessed. It occurred about 11 P.M. on the evening following that on which the first-described halo appeared. All three were followed by drenching rain, lasting about a week in the first case. A gale came shortly after the second (December 19th). The cirrhus clouds which almost filled the sky resembled in form an appearance of aurora on this occasion, and had a peculiar motion, vanishing and reappearing in fresh forms, though there was no wind at the time.

NOTICES OF SCIENTIFIC WORKS.

FARADAY, HIS LIFE AND LETTERS.*

ONE of the prettiest spots on the rail between Lancaster and Leeds is the village of Clapham. Here the bold Yorkshire scenery loses its nakedness, the hill-sweeps are cultivated, and a winding stream runs through the somewhat wooded valley. At a considerable elevation the railway bridges this valley, and as the station is neared a few scattered stone cottages mark the commencement of the distant village. This is the ancestral home of Faraday, and here his family name is still to be found. The Clapham parish register of 1708 contains the earliest record of the family of our great philosopher in the person of one "Richard Ffaraday." After this we find that at Clapham Wood Hall, there lived a Robert Faraday, one of whose sons, James, became a blacksmith. Soon after his marriage, in 1786, James Faraday moved to London, and lived for a while at Newington Butts, where his third child, Michael, was born on Sept. 22nd, 1791. This Michael was afterwards the "Faraday" whose name is now a household word, and the lustre of whose fame time will increasingly brighten.

The stages of Faraday's early life are well known; how, from being a newspaper boy, he rose to be a bookbinder's apprentice, then to be the assistant, and finally, the successor of Davy. It would, however, hardly be thought likely that the quiet and simple life of Faraday would furnish sufficient materials for so extensive a biography as that which Dr. Bence Jones has compiled. But it must be remembered that Faraday's life was full of his own stirring discoveries, and forms the link between the scientific men of the past and those of the present. The true function of a biographer is to sink himself in his subject, and this Dr. Bence Jones has done in an eminent degree. Hence the work reads like an autobiography. It gives us a picture of Faraday's intensely active and penetrating mind, from which there flowed at first sagacious letters to his friends; then a journal of foreign travel, full of acute observation; then a record of his early work in the laboratory; then his early triumphs as a lecturer; and, when he had fully trained himself for the fight, his grand conquests over the secrets of nature. So that one reads on with an eager and almost breathless interest as Faraday hotly pursues his electrical researches, and goes from strength to strength in the mysteries he reveals.

The first traces of Faraday's greatness of mind are to be found in his letters to his early friend Abbott. This correspondence, to

*The Life and Letters of Faraday,' by Dr. Bence Jones, Secretary to the Royal Institution. London: Longmans, 1870.