thus succeeded in rotating a hollow cylinder of mica, or r insulating substance, hung by a silk fibre, in the space osed by four vertical curved copper plates, to which the isite differences of potential were communicated. An acat of these interesting experiments (described to the ademia dei Lincei) will be found in the Naturwissenftliche Rundschau, No. 3, 1893.

ROF. R. C. SCHIEDT has been making some interesting ervations on oysters, and at a recent meeting of the Philaphia Academy of Natural Sciences Prof. Ryder reported on behalf that oysters which had the right valve removed and exposed to the light in this condition, in a living state for rtnight or so, developed pigment over the whole of the lermis of the exposed right mantle and on the upper exposed s of the gills, so that the whole animal from this cause imed a dark-brown colour. Animals so exposed not only mpted to reproduce the lost valve and hinge, but also partly ceeded in so doing, even re-establishing the insertion of the inutive pedal muscle upon the inner face of the imperfectly roduced right valve, which was deformed owing to the lack upport of the right mantle, because of the removal of the inal right valve. As a consequence the right mantle was ed up at the edge, and this deformation of the mantle was ected in the attempted regeneration of the lost right valve. : pigment developed during exposure to light in the mantle gills in oysters with the right valve removed, which were t alive in the aquaria at Sea Isle City by Prof. Schiedt, was olly confined to the epidermis as it normally is at the mantle ler in the unmutilated animal in nature. The inference to irawn from these facts is that the development of pigment in mantle and gills was wholly and directly due to the abnorand general stimulus of light over the exposed surface of mantle and gills, due to removal of the right valve, and that mantle border, the only pigmented portion of the animal, igmented because it is the only portion of the animal which ormally and constantly subjected to the stimulus of light. [R. D. CLEVELAND, of San Diego, California, contributes to nce an article in which he states some curious facts regarding trap-door spider (Mygale henzii, Girard), which is widely used in California. Behind San Diego there are many hilis about a foot in height and three or four feet in diameter. ese hillocks are selected by the spiders, Mr. Cleveland sugsts, because they afford excellent drainage and cannot be shed away by the winter rains. A suitable spot, which ays consists of clay, adobe or stiff soil, having been chosen, spider excavates a shaft varying from five to twelve inches in th, and from one-half to one and a half inches in diameter. is done by means of the sharp horns at the end of the er's mandibles, which are its pick and shovel and mining

The earth is held between the mandibles and carried to surface. When the shaft is of the required size, the spider ths and glazes the wall with a fluid which is secreted by f. Then the whole shaft is covered with a silken paper #g, spun from the animal's spinnarets. The door at the top he shaft is made of several alternate layers of silk and , and is supplied with an elastic and ingenious hinge, and closely in a groove around the rim of the tube. This door lates the surface on which it lies, and is distinguishable it only by a careful scrutiny. The spider even glues earth bits of small plants on the upper side of the trap-door, thus ng it closely resemble the surrounding surface. The spider rally stations itself at the bottom of the tube. When, by ing on the door, or by other means, a gentle vibration is ed, the spider runs to the top of its nest, raises the lid, and s out and reconnoitres. If a small creature is seen, it is d and devoured. If the invader is more formidable, the

door is quickly closed, seized, and held down by the spider, so that much force is required to open it. Then the spider drops to the bottom of the shaft. When the door of the nest is removed, the spider can renew it five times-never more than that. From forty to fifty cream-coloured spiderlings are hatched from the yellow eggs at the bottom of the nest. When these have attained only a fraction of their full size-before they are half grown-the mother drives them out into the world to shift for themselves. After a brief period of uncertainty they begin active life by making nests, each for itself, generally close to "the old homestead," sometimes within a few inches of it. These nests are

always shallow and slender, and are soon outgrown. When the spider attains its full size it constructs a larger nest.

AN interesting paper concerning the supposed volatility of the element manganese is contributed by Prof. Lorenz and Dr. Heusler, of Göttingen, to the current number of the Zeitschrift für Anorganische Chemie. Although the melting point of the metal is known with tolerable certainty to be about 1800° 1900°, much higher than that of iron, no information has yet been acquired concerning its boiling point. Profs. Lockyer and Chandler Roberts, however, so long ago as 1875 pointed out that the metal was volatile at the temperature of the oxyhydrogen blowpipe; and M. Jordan, in a communication to the Comptes Rendus in the year 1878, reported that in the manufacture of highly manganiferous spiegeleisen near Marseilles, a deposit very rich in manganese was usually found in the cooler portions of the furnace. Moreover, M. Jordan stated that during the casting of ferro-manganese red flames are produced, from which a heavy fume is deposited containing a large percentage of manganese. M. Jordan subsequently heated ferro-manganese to a white heat in a crucible in his laboratory, and ascertained that a diminution in the percentage of manganese actually occurred. These observations were considered somewhat surprising, inasmuch as the melting point of manganese is so high, in the neighbourhood of white heat, and it would appear that this volatility must be exhibited even at the melting point itself.

out.

PROF. LORENZ and his colleague have therefore conducted a series of experiments with the view of ascertaining whether manganese is really volatile per se, or whether the volatility is due to the intermediate action of carbon monoxide (derived from the carbon usually present) in forming a volatile but dissociable compound of a nature similar to nickel- and ironcarbonyl. It was first definitely proved that carbon monoxide does not combine with manganese below the temperature of 350°, a fact which M. Guntz has recently independently pointed Experiments were then made at higher temperatures, using a new form of combustion furnace, designed by Prof. Lorenz and fully described in the Zeitschrift, in which each individual burner is supplied with a blast capable of being regulated, the whole apparatus being equivalent to a row of blowpipes which will rapidly raise a thick porcelain tube up to a white heat. In the first series of these high temperature experiments coarsely powdered manganese containing seven per cent. of carbon was heated to whiteness in a glazed porcelain tube in a current of carbon dioxide, in order that nascent carbon monoxide might be produced in contact with manganese by the reduction of the carbon dioxide by the carbon present. After half-an-hour's heating the tube was allowed to cool in the stream of carbon dioxide and then broken, when it was found that a large quantity of the manganese had volatilised and condensed again further along the tube, in the form of a thick black deposit somewhat resembling zinc dust. Upon repeating the experiment with a current of carbon monoxide, a similar result was obtained. Hence manganese is certainly volatile in carbon monoxide. But it was afterwards found that equally good deposits of manganese dust were obtained when a current of

either hydrogen or nitrogen, neither of which combine with manganese, were employed. It is therefore evident that manganese does not resemble iron and nickel in forming a volatile compound with carbon monoxide, but that the volatility is a property of the element itself, and is singularly manifested even at the temperature of the melting point.

SOME of the more interesting captures recently made by the dredging staff of the Marine Biological Association at Plymouth are the Actinian Chitonactis coronata; the Nudibranchs Berghia cærulescens (new to Britain), Amphorina cærulea, and Lamellidoris oblonga in considerable numbers; and the handsomely marked rare spider-crab, Stenorhynchus egyplius. The alga Halosphæra viridis has been present in all townettings since October; and Noctiluca, though in small numbers, is now generally present. The breeding season of a large number of Invertebrata has already commenced, and the sea swarms with Copepod and Cirrhipede Nauplii, and with Polychate larvæ. Species of the following genera are breeding :-The Hydroids Halecium, Plumularia, Sertularella, Hydrallmania; the Actinians Chitonactis and Actinia; the Nemertine Lineus obscurus (larva of Desor); Phyllodoce maculata and other Annelids; the Molluscs Capulus hungaricus, Lamellaria, Buccinum, Purpura, many Nudibranchs; and the Decapod Crustacea Crangon, Pandalus, and Palæmon; Carcinus, Cancer, and Eurynome.

THE additions to the Zoological Society's Gardens during the past week include a Fallow Deer (Dama vulgaris 8) European, presented by Mr. B. L. Rose; a Great Eagle Owl (Bubo maximus) European, presented by Mr. Adolphus Drucker; two Gold Pheasants (Thaumalea picta ? ?) from China, presented by Miss Forster; nine Snow Buntings (Plectrophanes nivalis) British, presented by Mr. T. E. Gunn; an Egyptian Cobra (Naia haje), two Hoary Snakes (Coronella cana), from Victoria West, Cape Colony, presented by the Rev. G. H. R. Fisk, C.M.Z.S.; three European Pond Tortoises (Emys europea) European, deposited ; a King Snake (Coluber getulus) from North America, received in exchange.

OUR ASTRONOMICAL COLUMN. THE TOTAL SOLAR ECLIPSE OF APRIL 15-16, 1893.- The following particulars of the phenomena of the total solar eclipse of April 15-16, 1893, have been supplied to the Eclipse Com. mittee by Mr. A. M. W. Downing, Superintendent of the Nautical Almanac office, for the use of the English observers at the eclipse stations to be occupied in Brazil and Africa :Longitude 38° 50′ W. Latitude 3° 20' S. Contact Contact Sun's from from altivertical. tude. 19° W. ... 62°

Brazil.

d. h. m. S.

Eclipse begins April 15 22 18 14

15 23 40 51

15 23 45 34 16

N. point. 136° W.

Duration 4m. 43°1s.

45° E.

I II 40.. Local mean times.

...

84° W. ... 68°

1893. Feb. 16

RA. app. h. m. S.

Decl. app.

Log r.

Log

RELATIVE POSITIONS OF STARS IN CLUSTER X PETS Volume xxx. part iv. of the Transactions of the Ro Society contains the results of the investigations of Sir Ball and Mr. Arthur Rambaut, with respect to the positions of 223 stars in the cluster x Persei as dee photographically. The instrument used throughout was inch silver on glass reflecting telescope, mounted accor Cook's standard equatorial pattern. For the adjustme plate (the size used here being 3 × 3) and mirror [ stone Stoney's collimator was employed, this method etser exact perpendicularity of the photographic plate to the a collimator. The negatives were measured with an made by the same firm, and after the same pattern as the by Prof. Pritchard, at Oxford, this instrument being with the means of measuring either rectangular or p ordinates, the former of which has been adopted here In this memoir the authors treat in detail, by figures and formulæ, the equations for orientating the measurement, for computing the differences in Right and Declination from the centre of the plate, for com relative apparent positions of the stars for effects of tion, observation, nutation, and procession, &c. here given have been obtained from one photograph take an exposure of ten minutes, the images under the being susceptible "of very accurate measurement.

out.

negative has been employed is due, as the authors say, to sure of other work and to necessary alterations in the inment, but they hope to repeat the investigation next autumn. he table showing the positions, the authors compare their Its with those of Vogel and Pihl, and they find that a Il difference, depending on the adopted position of the fundatal star, is apparent between the former's declinations, while is right ascensions differ slightly, though systematically, this repancy being due very probably to the different methods of rmining the parallels. The memoir concludes with a map ving the relative positions of the stars plotted direct from and y coordinates.

ASTRONOMIE.-The February number of this journal cons many articles of interest. Prof. Stanislas Meunier gives an unt of a meteorite that fell in Algeria; this meteorite has ed to be of iron, containing as much as 91 32 per cent., and lished surface, when treated with an acid, showed the wellwn Widmannstätten figures. M. Flammarion, in addition account of "Les Pierres Tombées du Ciel," with reference Les Anciens Volcans de la Lune," lately advocated by Prof. sley in Astronomy and Astrophysics, gives the fourth of six chapters dealing with the question, "Comment vera la fin du Monde." M. J. Fényi, director of the Obtory of Kalocsa, gives an account of the enormous solar tion (383,000 kilometres high) that occurred on October 3 while a short note on some curious appearances undergone >met Swift includes six drawings by M. Lorenzo Kropp, 1 between March 18 and April 25, and the three photographs 1 at the Lick Observatory by Mr. Barnard, all of which ate the results of tremendous actions, whether they be due to fluences of different forces, " attraction, repulsion, chaleur, ricité, or changements d'état, qui ajissement sur ses gazeux dans leur voisinage du soleil." M. Weinck of ae describes the results of his examination of the Lick ives with reference to the lunar crater Flammarion, and a drawing (which, by the way, can be well seen by half g the eyes) of its surroundings, together with the three new s. This number also includes a general summary of the orology of the preceding year, the results being given in ammatic form, bringing out clearly the diurnal and monthly

jes.

PITER'S FIFTH SATELLITE.-Mr. Barnard, who has been uing his observations with respect to the fifth satellite of er, communicates the results he has obtained to the

nomical Journal (Nos. 285-86). The values of the ation distances deduced from the measures at elongaare, for eastern elongation, 48" 089 (±0.061), and for rn elongation, 47′′ 621 ((± 0·176), the probable errors of a -determination being 023 and 047 respectively. values are equivalent to the following distances:

E. elongation 112,500 143 miles
W.

III,412412

e values for the period he gives as

-:

Mountains of the Moon. In Urundi the kings were supposed to be lineal descendants of the moon, and the white traveller was hailed as being the returned ghost of a lately-deceased chief. On September 11 the expedition crossed the Akenyaru, which is not, as supposed, a lake, but a river, though the name "Nyanza" is often applied to it. Dr. Baumann also discovered that the so-called Lake Mworengo is in reality a river which flows into the Akenyaru, and came to the conclusion that there was no extensive sheet of water in Ruanda or North Urundi. On September 19 Dr. Baumann arrived at the source of the Kagera (Alexandra Nile), which rises at the foot of the precipitous and wooded hills which form the watershed between the basins of Rufizi and the Kagera. This mountain chain is known to the natives by the name of the "Mountains of the Moon," and is held in peculiar reverence by them. Here Dr. Baumann maintains the real source of the Nile to be, for if "it be acknowledged that the Kagera is the chief feeder of the Victoria Nyanza, it follows that the headwaters of the Nile can be none other than those of the Kagera itself in the Mountains of the Moon in Urundi, within the boundaries of German East Africa."

THE often-discussed scheme of an expedition to the North Pole by way of Franz Josef Land has been revived by Mr. F. G. Jackson, who proposes to lead an expedition next summer, if the means for equipping a ship are forthcoming. Mr. Jackson's. plan is to travel with a small party, and establish a chain of depots northward from the most northerly accessible landing-place in Franz Josef Land. He would remain during winter in the most advanced post, and push on each summer with dog-sledges, until the pole is reached. The plan rests on the hypothesis of Franz Josef Land extending to the pole, just as Dr. Nansen's rests on the hypothesis of a transpolar current, but the evidence of the great extension of the land is not very satisfactory. Mr. Jackson's previous Arctic experience is not stated, nor is there any indication given as to whether he intends to travel at his own expense or to appeal for pecuniary help.

THE British South African Company have reserved the Zimbabwe Ruins and the area within a radius of one mile from the top of Zimbabwe Hill for archæological and scientific purposes, and no settlements, farms, or mines will be permitted within that radius.

A BEAUTIFULLY illustrated report on the regulation of Swiss torrents, by the late M. de Salis, has recently been published by the Swiss Government. The natural erosion and surface change which go on at the present day so rapidly among the steep slopes of a mountainous country as to be frequently cataclysmic in their intensity, have to be avoided or endured in inhabited regions. A frequent source of floods is the damming up of a large river by the mud and stones brought down by a freshet in a small tributary. The method of combating this effect is to build a succession of weirs, and cut a parallel canal so that the sediment is caught and the overflow regulated before the escaping water reaches the main valley.

MR. MACKINDER's fourth Royal Geographical Society's educational lecture, delivered last week, dealt with Central Asian trade- and travel-routes, under the title of "The Gates of India and China."

ean, when proportional weights are applied, being

TWENTY YEARS IN ZAMBESIA.

MR. F. C. SELOUS, the famous hunter and explorer of

South Central Africa, gave a summary of his travels to the Royal Geographical Society on Monday evening. His address was illustrated by an exhibition of unusual interest in the tearoom, where a large collection of stuffed specimens of the characteristic African mammalian fauna was arranged. Photographs and various objects illustrative of the rapid development of Mashonaland since the Chartered Company took possession were also shown.

Mr. Selous commenced his African wanderings in 1871, and except for occasional visits to England he has travelled and traded in that continent ever since. In 1872 he and some companions penetrated into Matabeleland to hunt elephants, and had an amusing interview with the chief, Lo-Bengula. Although at that time not an explorer in the scientific sense, the accurate memory of his early wanderings over the country enabled Mr.

Selous to successfully guide the Pioneer Force of the Chartered Company in 1890, when they took possession of Mashonaland. With regard to the health of Zambesia he says:-" Owing to severe exposure to wet and cold during several days and nights, in the early part of 1872, I got an attack of fever and ague in Griqualand so that I was handicapped before starting for the interior. This fever and ague was exactly what I have seen people get on the high plateau of Mashonaland, during the last few years, from similar exposure to rain and cold. It took me some time to shake off, and was still in my system when I reached Matabeleland, but the attacks only came on when I halted anywhere for a few days. During November and December, 1872, hunting down in the low hot country towards the Zambesi, I was again very much exposed to wet, and on several occasions lay out all night long, without any shelter, drenched through with such heavy rain that it put out the largest fire and converted hard ground into a swamp. I naturally again got soaked with fever poison, but as long as I remained hunting the disease did not show itself. Directly I got back to Bulawayo it broke out, and during a month or so I had several sharp attacks. By that time, however, my sound constitution had choked all the fever germs, and from that day until in 1878, when very severe exposure in Central Africa once more filled me up with malarial poison, I do not remember ever to have had one single hour's illness, or to have taken one drop of medi cine. The life I led was, however, if a very hard, at any rate, in many respects, a very healthy one; for the most part I ate nothing but meat and Mashona rice, and drank nothing but tea, usually without milk and sugar-not because I like it so, but because those adjuncts were unobtainable."

North of the Zambesi Mr. Selous made several journeys among the Batongas, and spent a wretched rainy season, almost without equipment, on the Manica table land. After the rains the country looked charming. The young grass, thanks to the recent heavy rain, had shot up one foot or eighteen inches in height over hill and dale, every tree and shrub was in full leaf, and everything looked green, and fresh, and smiling. Many of the shrubs on the edge of the hills bore sweet-smelling flowers, and, as on all the plateaus of the interior of Africa, small but beautiful ground-flowers were very abundant.

Interesting observations were made on some of the northern rivers. The curious phenomenon of the steady rise of the waters of the Chobe and Machabi-an outlet of the Okavango-was observed from the first week in June until the last week in September, when they commenced to recede. That the Okavango and the Upper Kwando are connected on their upper courses, there can be little doubt, as the waters of the Machabi went on rising suddenly pari passu with the Chobe, until the end of Sep. tember, when both commenced to recede simultaneously.

The explanation of this remarkable phenomenon is difficult, as there are no snow mountains at the sources of the Kwando and Okavango rivers and the Zambesi, which rises in the same latitude, decreases steadily in volume from day to day during the dry season like almost all other rivers in South Central Africa. Besides the channels which still become annually filled with water from the overflow of the Chobe and Okavango river systems, there are many others which are now quite dry, but in which the natives say they once used to travel in canoes.

From 1882 the journeys acquired additional geographical importance, and Mr. Selous proceeded to rectify the maps of Mashonaland laid down by earlier travellers, taking constant compass bearings, sketching the course of rivers, and fixing the position of the junction of tributaries. The value of this work was made manifest in a magnificent large scale map of the country, drawn as well as surveyed by Mr. Selous, which was used to illustrate the lecture. It would be impossible, without practically reproducing the whole address, to do justice to the immense variety and solid value of the contributions to African geography made by this most energetic of pioneers; or to the thrilling adventures, the recital of which was listened to with breathless attention and greeted with the heartiest applause. With the exception of a treacherous night attack made upon his camp by the Mashuku-sumbwe, led by a few rebel Marotse, in 1888, he had never had any other serious trouble with the natives. During his twenty years' wanderings he went amongst many tribes who had never previously seen a white man, and he was always absolutely in their power, as he seldom had more than from five to ten native servants, none of whom were ever armed.

THE DISTRIBUTION OF POWER BY ELECTRICITY FROM A CENTRAL GENET ING STATION.

ON Friday evening, the 3rd inst., Mr. A. Siemens deliver the Royal Institution an interesting lecture on the w which science is applied to practice. In the course of the e he made the following remarks on the distribution of pos electricity from a central generating station :—

Before entering further into this, let me remind you earliest magneto-electric machines were used nearly sixy ago for the production of power. I will mention only electric launch of 1835 as an example. It must, therefor considered altogether erroneous to ascribe the invention transmission of power to an accident at the Vienna Ex in 1873, when, it is said, an attendant placed some stra into the terminals of a dynamo machine; it began to the transmission of power was first demonstrated. Asi of fact, Sir Wm. Siemens once informed me, that his Werner was led to the discovery of the dynamo-electric p by the consideration that an electro-magnetic machine bu like a magneto-electric machine, when a current of en was sent into it, viz. both turn round and give out pow was, of course, well known that a magneto-electric m produces a current of electricity, when turned by mec power, and Werner concluded that an electro-magnetic would behave in the same manner. We all know that right, but I relate this circumstance only as a further prom the generation of power by electric currents has been. known fact long previous to the Vienna Exhibition.

Another well-known instance of transmission of pers distance is furnished by the magneto-electric ABC instruments, where the motion at the sending end suppiz currents necessary to move the indicator at the receiving s

As an illustration of the distribution of power by elettr will briefly describe some radical alterations that have be at the works of Messrs. Siemens Brothers and Co., by th duction of electric motors in the place of steam engines

[A diagram on the wall showed in outline the various b in which work of different kinds is carried on with the different machines.]

Electric motors are supplying the power, sometimes ving shafting to which a group of tools is connected by and sometimes by being coupled direct to the moving Each section of the works has its own meter, ze the energy that is used there, and all of them are coast, underground cables to a central station, where three engines and dynamos generate the electric current for all There are two Willans and one Belliss steam engines 300 horse-power, coupled direct to the dynamos, and run a speed of 350 revolutions per minute. Room is fourth set, but including some auxiliary pumps and the boards for controlling the dynamos and for distributing rent, the whole space occupied by 1200 horse-poweronly 32 42 feet. Close by are the condensers and thre pressure boilers, which have replaced some low-press formerly used for some steam engines driving the ma the nearest building.

The advantages that have been secured by the introd electric motors may be briefly stated under the heads :

1. Various valuable spaces formerly occupied by strat and boilers have been made available for the extensi shops, and these are indicated on the diagram by s

2. By abolishing to a great extent the mechanical tra of power a considerable saving is effected in molt which is especially noticeable at times when part o machinery is in use.

3. As the electric motors take only as much current w ally required for the work they are doing, a further effected, and at the same time the facility with which of the motors can be altered without their interfering other presents a feature that is absent from mechan mission.

4. The big steam engines being compound and produce a horse-power with a smaller consumption the small high-pressure steam engines scattered thr works.

The numerous attendants of the old steam engines and rs have mostly been transferred to other work, only a few em are required at the central station, and one or two men asily look after all the electric motors used in the various of the works.

sewhere equally favourable results have been obtained by ntroduction of electrical distribution of power, and in this ct I beg to refer you to a paper read before the German tution of Civil Engineers by Mr. E. Hartmann in April of year, and to a paper read by Mr. Castermans before the ety of Engineers in Liège, in August last, in which he pares in detail various methods of transmission of power, of h the electrical one was adopted for a new small arms ry.

may therefore take it for granted that the advantages led to above have not resulted from local circumstances at lwich, but that they can be realised anywhere by the adopof the electric current for distributing power from a central

first sight this result appears to be of interest only to the ufacturer; but the development of this idea may lead to eaching consequences, when we consider that cheap power e of the most important requisites for cheap production. hile power was generated by steam engines the cost of acing one-horse-power varied a good deal in the different and the various owners could not have obtained their ron equal terms, those possessing the largest steam ies having a distinct advantage. This inequality is done with altogether when the power is distributed by elecy, as the current can be supplied for large or small powers e same rate per Board of Trade unit. It is therefore that the establishment of central stations for the generation ectricity on a large scale will bring about the possibility of works competing with large works in quite a number of s where cheap power is the first consideration.

other circumstance favouring small works is the diminution pital outlay brought about by the employment of electric rs. Not only are the motors cheaper than boilers and engines of corresponding power would be, but the outlay lting and shafts is saved, and the structure of the building not be as substantial as is necessary where belts and shaftave to be supported by it. A commencement has already made in this direction by the starting of electric light ns, where the owners do all in their power to encourage se of the current in motors, in order to keep the machinery eir central station more uniformly at work. The intro on of electricity as motive power will apparently present a g contrast to the effect steam has had on the development lustries for the reasons already stated; and in addition are many cases where the erection of boilers and steam es, or even of gas engines, would be inadmissible on nt of want of space or of the nuisar.ces that are inseparable them. Motive power will therefore be available in a er of instances where up to the present time no mechanical could be used, but the work had to be done by manual or not at all.

1 may have noticed that I have confined my remarks to to the case of distributing electricity over a limited area, at I have not yet discussed the question of transmitting to a great distance.

coretically we have been told over and over again that the e power of the future will be supplied by waterfalls, and heir power can be made available over large areas by of electric currents. As a prominent example the inon is constantly mentioned by which the power of a e at Lauffen was transmitted over a distance of 110 statute

o the Frankfurt Exhibition with an efficiency of 75 per No doubt this result is very gratifying from a purely fic point of view, but unfortunately in practical life only ercially successful applications of science will have a lasting ace, and in this respect the Lauffen installation left much Cesired. On the one hand science tells us that the section conductor can be diminished as the pressure of electricity eased, and it appears to be only necessary to construct tus for generating electricity at a sufficiently high pressure o reduce the cost of a long conductor to reasonable limits. - other hand, experience shows that at these high potentials ulation of the electric current becomes a most difficult m, and for practical purposes difficulty means an increased of money.

MAGNETICAL AND METEOROLOGICAL OBSERVATIONS MADE AT THE GOVERNMENT OBSERVATORY, BOMBAY, 1890, WITH AN APPENDIX.

And in

THIS volume, we are informed, is the thirtieth of the series of "Bombay Magnetical and Meteorological Observations," extending the previous record from 1845 to 1889, up to 1890. At this well-organized observatory, under the direction of Mr. Charles Chambers, continuous registration of the different magnetical and meteorological elements is maintained by means of automatic recording instruments, of which there are five sets, the magnetographs (three), the barograph, the thermograph, the pluviograph, and the anemograph, all being photographic records excepting that of the anemograph, which is mechanical. In addition eye observations are also made, including the usual meteorological observations of weather and other phenomena. Daily values for 1890 are given of atmospheric pressure, temperature of the air, rainfall, wind and cloud, with some further discussion of the anemometric results; five day means of meteorological elements are also given. In the magnetic section is found observations of absolute horizontal force, magnetic declination and dip, at short intervals throughout the year. the appendix is contained a collection of the monthly values of declination and horizontal force from 1868 to 1890, accompanied by a discussion of the secular changes of these elements. In regard to declination the results show the eastern magnetic declination to have increased during the early years of the series, arriving at a maximum at about the middle of the period, and decreasing in the later years. Taking the annual values of declination to be represented by the formula dat2+bt+c, it is found that the maximum easterly declination occurred in 1880, with value o° 57′ 17". This actual observation of the turningpoint at this place, in the long cycle of change, is very interesting. The horizontal force values are similarly discussed, but in this case the values are generally progressive. There is no discussion of diurnal inequalities, but these were elaborately treated in a previous volume. Magnetic observatories in tropical and southern regions are valuable. Many exist in Europe with others scattered over different parts of the northern hemisphere, generally publishing with regularity their results, but there is a want of similar establishments in southern regions. There are magnetic observatories at Batavia, Mauritius, and Melbourne, but we do not get from them all that might be desired. England possesses no regularly maintained southern establishment of this kind. A magnetic observatory existed many years ago at the Cape of Good Hope, which, long since destroyed, we believe, by fire, was never again reorganized, which was unfortunate. The attention of the Magnetic Committee of the British Association was several years ago drawn to the question of re-establishing the Cape Magnetic Observatory, and in the Report of the Committee for the year 1891 it is stated that a representation had been made to the Admiralty as to the desirability of so doing. An efficient magnetic observatory in such a position, with regular publication of the results, would provide information of great value for the discussion of various questions in magnetic phenomena that now arise. It would be well also if the study of earth currents were taken up at some of the magnetic observatories in different parts of the world by continuous photographic registration thereof, for the better elucidation of the physical relation that may exist between magnetic and earth current variations, in regard to which our knowledge seems at present to be so imperfect.

BACTERIA AND BEER.

THE examination of water for micro-organisms since the publication by Koch in 1881 of his beautiful process of gelatineplate cultures has come more and more into general use, as the public has gradually become cognisant of its value for hygienic and practical purposes. But whilst affording much valuable information on many subjects, Hansen has pointed out, as far back as 1888, that as applied to the examination of waters for brewing purposes it cannot be considered wholly satisfactory. Working on lines suggested by Hansen, Holm has recently published a paper, Analyses biologiques et zy motechniques de l'eau destinée aux brasseries" (Compte-rendu des travaux du laboratoire de Carlsberg, vol. iii., Copenhagen, 1892), in which he describes a large number of investigations on brewing-waters examined by Hansen's method, and in which the relative merit for brewing