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vented by Mr. D. R. S. Galbraith, a constant stream of iron sand mixed with a given quantity of carbon is fed in at the top of the furnace, and travelling downwards by gravitation falls between and upon graphite bars forming resistances in the circuit, and finally leaves the furnace in the form of molten metal. The power is supplied by a single-phase alternator having an output of 100 kilowatts at 300 volts. This pressure is reduced to 18 volts by means of a transformer in close proximity to the furnace. The plant is, of course, an experimental one, and will require to be modified in several ways before it is used on a commercial scale.
DR. J. JOLY, F.R.S. (Scientific Proceedings of the Royal Dublin Society, vol. x., No. 34), being struck by the difficulties raised by the silting up of harbours on the south-east Irish coast, suggests the use of floating breakwaters moored to the bottom, but sufficiently deep to prevent response to the rise and fall of waves. They would thus be affected only by the tidal movements, and the dimensions" need not be extravagant where the conditions are not such as to require protection from deep-water waves." Two types are illustrated, the one cylindrical, with a submerged platform below, going down to about fcur fathoms, and the other more like a flat-bottomed ship, wider below and narrower above, with a hold full of water to increase the inertia. The author believes that in the seas inside the banks of Wicklow and Arklow such a mass might be assumed to be unaffected by wave-motion. The presence of such a breakwater, it is suggested, might even favourably increase the tidal scour.
WE have received from the Home Office part iv. of the general report on mines and quarries for 1903, containing comparative statistics relating to persons employed, output, and accidents at mines and quarries in the British colonies and in foreign countries. A good idea is given of the relative importance of mining in each country. In 1903 the number of persons engaged in mining and quarrying was 4,861,932, of which one-fifth were employed in the United Kingdom and one-third in the British Empire. More than half the total were employed in getting coal, of which the world's production was 881,002,936 tons. The world also produced 609,985 tons of copper, 491,672 kilograms of fine gold, 44,548,962 tons of pig iron, 892,899 tons of lead, 26,232,099 tons of petroleum, 12,818,253 tons of salt, 4,997,491 kilograms of fine silver, 98,295 tons of tin, and 570,440 tons of zinc. The death-rate from accidents throughout the world in 1903 is estimated at 1.83 per 1000, as compared with 1.93 per 1000 in 1902. For coal mines the accident death-rate of the United Kingdom is 1.26, and for the British Empire 1.33; while for France it is 1.02, for Germany 2.00, and for the United States 3-09. The death-rate for foreign countries generally is 2.14. It is evident that mining is conducted in Great Britain with a far smaller risk of accident to the workers than in most other countries.
THE meteorological results deduced from the observations taken at the Liverpool Observatory, Bidston, for the year 1904 have been published by Mr. W. E. Plummer. This observatory is maintained by the Mersey Docks and Harbour Board, and is one of the oldest and best equipped in the United Kingdom. Many years ago, the late Mr. W. W. Rundell prepared an elaborate discussion of the winds of Liverpool, which was published by the Meteorological Office. We notice that at the present time much attention is paid to this subject, which is naturally of the greatest importance for the shipping of the Mersey.
Three anemometers of the Osler, Robinson, and Dines patterns are kept in efficient operation, and the maximum velocities and extreme pressures of the wind on the square foot are given for each day of the year, while the monthly and yearly summaries of the principal meteorological elements are expressed in imperial and metric measures. In the astronomical department, the transit instrument has been used continuously for the determination of time, and 2586 stars were observed during the year.
We have received the annual report of the director of the Royal Alfred Observatory (Mauritius) for 1904: it contains the means and extremes of the meteorological elements and other general information; the actual observations will be published in a separate volume. From a table showing the observations of the direction of the various types of clouds, it is noteworthy that out of 821 observations the cumulus cloud was observed on 397 occasions, the cirrus cloud on only 66 occasions. The mean annual rainfall at ten selected stations was 13 inches below the average. The log-books of ships visiting the island were copied, and a daily journal of the weather over the Indian Ocean kept; it is noticeable that the number of vessels arriving annually between 1882 and 1904 have steadily decreased from 686 to 262. Photographs of the sun were taken daily whenever possible; 638 negatives were forwarded to the Solar Physics Committee. During the year 65 earthquakes were recorded. The observatory is still much troubled by depredations of white ants; numerous poisons have been tried for their extermination, the most efficacious being a solution of sal-ammoniac, turpentine, and methylated spirit, while the bookshelves are insulated with castor oil.
ONE of the scientific results of the annexation of the
Philippines by the United States is the study of the ethnography of the group. Mr. W. Allan Reed has published a report on the Negritos of Zambales (vol. ii., part i., Ethnological Survey Publications, Manila, 1904). This is in reality only a sketch, as the author was only two months in the field, but his observations have undoubted value; doubtless a more thorough study will be made of these interesting people. The sixty-two plates which illustrate the paper add very considerably to its value, and by their means one can gain a very good idea of these jungle folk. A very useful album of Philippine types by D. Folkmar has been published by the Philippine Exposition Board, Manila; it contains eighty plates of photographsfull-face and side view of head-of inmates of Bilibid prison. The author has been careful to select typical examples from various districts, and opposite each plate are given certain measurements of the individual photographed, together with the averages of the same measurements taken on a large number of examples of that particular tribe. This is a very useful device, as it gives some sort of clue as to whether the individual figured is a fairly typical example of his tribe.
WRITING to La Sicilia, Prof. A. Ricco mentions that the crater of Etna is extending towards the north-west, and along the whole of the circumference, from north to west, is a great continuous fissure emitting steam and heated vapours. As the whole of the ground between this fissure and the margin must fall into the crater, he warns intending visitors of the need of caution in approaching the crater from the westwards, the direction from which it is most easily accessible.
IN the May number of the Rend. Acc. Lincei A. Pochettino describes the luminescence emitted by certain crystals under the action of radium and Röntgen rays.
THE question What is research? is discussed by Prof. Henry S. Williams in the Popular Science Monthly. The author considers that research is not a special faculty possessed by the few, but a common faculty specially trained and systematically exercised by the few, for whom it becomes a tool of the highest value, and the means of opening up new fields of knowledge to mankind. At the same time, he directs attention to the detrimental effects of too much book learning on the power of research, and the need of a vivid imagination such as can be exercised and disciplined by the study of mathematics. Moreover, the man of research must be prepared to sacrifice his prospects in other directions and to work alone, "unappreciated and unapplauded" in most of his work, and Prof. Williams finally cautions teachers against tempting mere enthusiasts to undertake a task which requires for success the toughness of a soldier, the temper of a saint, and the training of a scholar. The subject of the article is one which might be very well discussed further in view of the large amount of "research," falsely so-called, which is now being turned out by persons not possessing any of these qualities, with the great danger of lowering public estimation of the importance of work of real scientific value.
DR. J. HETTINGER, writing from London in the Physikalische Zeitschrift for June 15, describes a new electrical connection for intensifying the resonance effects in wireless telegraphy.
THE Mathematical Association has reprinted the report of its committee on the teaching of elementary matheLittle matics. In the same pamphlet are reproduced the “ Go" regulations in geometry. We observe that Cambridge advocates the "hard pencil," which leads to SO many indistinct figures in candidates' answers. A valuable mental training is thus omitted in not requiring candidates to make their drawings, as well as written work, clear and distinct to others. Moreover, even a soft pencil with a thick point has an advantage in showing that in any constructive proof lines must necessarily be of a certain thickness, and the conclusion is only established as approxi
mately true. The beginner who learns this will be the better able to appreciate the deductive method at the proper time.
THE surfaces obtainable by the deformation of a hyperboloid of revolution of one sheet are discussed by Prof. Luigi Bianchi in the Atti of the Lincei Academy, xiv., 10. The determination of these surfaces is shown to depend on that of a certain class of imaginary pseudospherical surfaces, and the difficulty of the problem is reduced to that of characterising these latter surfaces, and thus presenting the final transformation formulæ in a real and definite form.
THE Institution of Electrical Engineers has published an address delivered to its students in January last by Mr. James Swinburne, M. Inst.C.E., on "The Theory of Electricity and the Value of its Study to Engineers." In it the author emphasises the desirability in many cases of mathematics being learnt through its applications, and points to the theory of electricity as affording a valuable introduction to the study of many of the most important branches of mathematical analysis. In conclusion the author says:-" I feel confident that enough has been said to make it evident that a modern engineer cannot consider his technical equipment complete without some knowledge of the theory of electricity; and if electrical development continues at the present rate it may soon be the most important branch of the science of engineering."
Biologisches Centralblatt of July 1 contains the report of an interesting address on the use and place of hypotheses, suppositions, and problems in biology, delivered by Mr. J. Reinke at the opening session of the International Botanical Congress at Vienna on June 12. That theories and hypotheses have a great and important place in science -indeed, that they are absolutely essential to its proper advance the lecturer fully admitted; but, he added, it is necessary to remember that they are nothing more than theories, otherwise there is the greatest danger of their proving a hindrance and an illusion. A notable instance of this danger is afforded by the numerous phylogenies of animals and plants which are published from time to time, and are too often accepted as though they were solid facts, instead of being in most cases mere hypotheses, based not unfrequently on the very slenderest of foundations.
A YEAR ago we referred to notices of the occurrence of the striped hawk-moth in this country, and we observe that in the Entomologist for June and July several instances of the capture of the same species this season are mentioned. Possibly this handsome moth may become established in the south of England, at least for a time. In the July number Mr. G. W. Kirkaldy continues his popular synopsis of British water-bugs.
To the Journal of Conchology for July Mr. A. D. Darbishire contributes a discussion on Prof. Lang's experiments in breeding with the common garden snails Helix hortensis and H. nemoralis. The writer denies that these experiments confirm the truth of Mendel's doctrine, stricto sensu; that is to say, they do not afford conclusive evidence of the existence in the gonads of H. hortensis of definite unit-bearing elements representing either five-banded or unbanded shells. It is added that much interest will attach to the description of the characters of the "dart" in the hybrid between the two species in question.
In the course of a paper published in the June nuinber of the American Naturalist on the advantages presented by the common skate as a subject for demonstration to anatomical classes, Dr. H. W. Rand takes occasion to emphasise the importance of selecting generalised, in place of specialised, species for such demonstrations. A skate or a dog-fish is thus to be preferred to a bony fish, and similarly a salamander to a frog. As regards the choice between a skate and a dog-fish, although the former is a much more specialised type than the latter, it has the advantage of being more easily obtained and of being available for the greater part of the year. Moreover, its very specialisation happens to be an advantage to it as an object for demonstration, for not only does its flattened form render it admirably suited for dissection, but most of its organs are brought more or less nearly into one horizontal plane, so as to be capable of demonstration almost as if drawn in a diagram. Apropos to this article is a second, by Messrs. Rand and Ulrich, on posterior connections of the lateral vein in the skate. To the same issue Mr. E. W. Berry contributes an article on fossil sedges and grasses, with the description of a new Carex ; and Mr. J. A. Cushman one on the fossil crabs from the well known Miocene beds of Gay Head, Mass., described long ago by Dr. E. Hitchcock, and subsequently by Sir C. Lyell.
AN interesting paper on the gradual dissociation of mellitic acid is contributed by A. Quartaroli to the current number of the Gazzetta Chimica Italiana, vol. xxxv. p. 470. The author has measured the rate at which cane sugar is inverted by mellitic acid and by the corresponding mono-, di-, tri-, tetra-, and penta-sodium salts in onetenth molecular solution. If the velocity constant for the free acid is represented by 100, the values for the various salts in the order given are respectively 40.5, 14.3, 2.2, 1.5, and 1.04. These numbers may be taken as a measure of the relative tendencies to ionisation of the six successive acid hydrogen atoms. Taking the ratio of the first to the second, of the second to the third, &c., the series 2.47, 2.82, 6.49, 147, 1-43 is obtained. These numbers are interesting, and the occurrence of a maximum value in the middle of the series suggests that the dissociation of mellitic acid is of abnormal character.
DURING the past week the Royal College of Surgeons of Edinburgh has been celebrating its four hundredth anniversary. The college, which is the oldest medical or surgical corporation in the United Kingdom, dates from July 1, 1505. The Royal College of Physicians of London, the next in point of age, was officially established some thirteen years later, i.e. in 1518. The current number of the Lancet contains an interesting account of the older institution.
THE third number of the second volume of the Investigations of the Departments of Psychology and Education of the University of Colorado has reached us. Among other contributions, those in which Prof. Francis Ramaley deals with the teaching of botany and zoology, and Prof. Chas. A. Lory with the teaching of physics, are of special interest.
WE have received a copy ot "Southern Rhodesia, Information for Settlers," a small handbook issued by the British South Africa Company. The title sufficiently indicates the nature of the contents of the book, but it is worth noting that many of the numerous illustrations are of considerable geographical interest and value.
THE report of the Royal Cornwall Polytechnic Society for 1904 has just been published, and bears testimony to the continued vitality of the society. One of the chief features of the society's activities during the year was its exhibition, in connection with which addresses and papers were given on electrical research, practical bee-keeping and management, and the geology, minerals and mines of Lelant, St. Ives, and Zennor. The first and last of these communications are to be found in the report before us, as is also an informing paper by Mr. C. C. Bignell on the aphides with their food plants; the volume likewise contains a detailed report of the work accomplished at the Falmouth Observatory.
THE new number of the Quarterly Review contains only two papers dealing with scientific subjects, one on the national coal-supply, the other, by Sir Charles N. Eliot, on the Buddhism of Tibet. Both communications are very informative and eminently readable.
MESSRS. R. AND J. BECK, LTD., of Cornhill, have just issued a catalogue of microscopes and apparatus specially suited for metallurgical work.
2h. 15m. p.m.
End of the eclipse.
Magnitude of eclipse=0.786. Sun's altitude at noon = 48°. PHOTOGRAPHS OF THE MARTIAN CANALS.-Since the opposition of Mars in 1901, persistent efforts have been made at the Lowell Observatory to secure photographs of the planet on which the canals could be seen definitely. After making a number of exposures with a camera in which the film was continuous, so that a large number of short exposures-as in the bioscope-could be made on the one film, Mr. Lampland succeeded in obtaining negatives which demonstrate indubitably the actual existence of the canals Nilosyrtis, Pyramus, Casius, Protonilus, Astaboras S., and Thoth. In addition to these, the regions Syrtis Major, Mare Erythrææum, Mare Icarium, Hellas and the north polar cap, and the " oasis Lucus Ismenius are plainly discernible. A photographic print from a negative secured on May 11 at 19h. 44m.48m. (G.M.T.) on which these features are visible is affixed in the Lowell Observatory Bulletin, No. 21, accom. panied by a drawing made by Mr. Lowell immediately before the exposure was made. Other photographs secured
show other canals, and Mr. Lampland is to be congratulated, in company with Mr. Lowell, upon thus securing unquestionable evidence of the actual existence of these features.
A point of special interest to planet observers is that whilst trying to obtain these photographs the observers found that the restriction of the aperture employed, by its elimination of the evil effects of atmospheric vibrations, more than counterbalanced the inconvenience caused by the diminution of light-gathering power and the consequent increase of the length of the exposures, a result which confirms the conclusion previously arrived at by Mr. Lowell from visual observations.
DUTCH OBSERVATIONS OF THE CORONA.-Parts iii. and iv. of Prof. Julius's report on the observations made by the Dutch expedition in Sumatra during the total solar eclipse of May 18, 1901, minutely describe the apparatus and the methods of procedure employed in examining the coronal radiations for polarisation effects and for the determination of the amount of heat radiated by the eclipsed sun.
A double-image polarimeter of the Cornu pattern, slightly modified, was employed to examine the polarisation at different points of an image of the corona. The points examined were situated at different distances from the sun's limb, and the position of each was carefully recorded. The results showed that the coronal rays were more strongly polarised at some distance from the limb than nearer to it, whilst at greater distances the polarisation again decreased. A discussion of some experiments, performed after the eclipse, on the depolarising effect of haze and clouds showed that this effect was practically negligible.
The observations of the total heat radiated by the eclipsed sun were made with a thermopile pointed directly to the corona, but clouds robbed the observations of any definite result. So far as they go, the resulting figures show that the heat radiated at totality is not so great as that received from the full moon, and that a very striking increase occurred after the third contact.
THE NORTH POLAR SNOW-CAP ON MARS, 1904-5.— Observations of the north polar cap of Mars were made at the Lowell Observatory by Messrs. Lowell and Lampland during the period November, 1904, to May, 1905. and the observers' notes for each night are given in full in No. 20 of the Lowell Observatory Bulletins.
One remarkable feature observed was a white collar which surrounded the cap during the latter half of January. Mr. Lowell explains this phenomenon by the conjecture that it is a belt of spring haze which surrounds the cap during the hotter months of the melting, the cap proper being bordered by a blue belt of material (probably water) produced by the melting of the snow. Several subsidiary patches of snow were left behind by the receding polar cap, and became prominent features.
Of these, one in longitude 206° was especially marked, recorded in exactly the same longitude by Schiaparelli in 1888, and independently at the Flagstaff Observatory in 1901 and 1903.
VEGETATION AND THE SUN-SPOT PERIOD.-Since 1871 M. Camille Flammarion has each year recorded the dates on which the chestnut trees in the avenue of the Paris Observatory have burst into leaf and flowered. Plotting the results of his observations with the sun-spot curve on the same year-scale, he found that the variation of the dates of the different phases of the annual arboreal phenomena agreed very closely with the latter curve, the leafbuds bursting and the flowers appearing earlier at those epochs when the sun-spot maxima occurred. The details of the observations and the method employed in reducing them are given in the July number of the Bulletin de la Société astronomique de France.
VISIBILITY OF THE DARK HEMISPHERE OF VENUS.-In a paper on the influence of the solar-activity variations on the planets, M. Hansky directs attention to the greater visibility of the dark hemisphere of Venus during epochs | of maximum solar activity. According to the theory of Arrhenius, electrified ions emitted by the sun cause the phenomena of terrestrial magnetic storms and aurora. Applying the same theory in the case of Venus, M. Hansky suggests that during the periods of solar maxima the,
dense atmosphere of that planet is rendered more phosphorescent, and, therefore, more easily visible, by the increased solar activity. He further suggests that, in order to test this theory, astronomers should observe the planet as often as possible during the present sun-spot maximum (Bulletin de la Société astronomique de France, July).
DETERMINATIONS OF METEOR RADIANTS.-Some interesting results of meteor observations are recorded in No. 4032 of the Astronomische Nachrichten by M. Eginitis, of Athens, and by Prof. A. A. Nijland, of Utrecht.
M. Eginitis observed the Perseid, Leonid, and Andromedid showers of 1903 and the Perseid shower of 1904. He gives the time of observation, the number, colour, magnitude and relative velocity of the meteors recorded, and the position of the determined radiant on each date, directing special attention to any objects which were, for any reason, extraordinary. On August 11, 1904, several meteors were seen to proceed from a radiant near to a Persei, and these were, in general, whiter and brighter than those from Persei, the latter being fainter and of a reddish-yellow colour, and generally falling in pairs.
Prof. Nijland's results deal with the Lyrid, Perseid, and Leonid showers of 1902, 1903, and 1904, and he gives the results for each night of observation and the positions deduced for the respective radiants.
THE INSTITUTION OF NAVAL ARCHITECTS. THE summer meeting of the Institution of Naval
Architects was held last week in London, the usual sittings for the reading of papers taking place in the theatre of the Society of Arts. The following papers were on the programme for reading and discussion:-Tactics and strategy at the time of Trafalgar, by Admiral Sir Cyprian Bridge; the ships of the Royal Navy as they existed at the time of Trafalgar, by Sir Philip Watts, Director of Naval Construction; the classification of merchant shipping, illustrated by a short history of Lloyd's Register, by H. J. Cornish, chief ship surveyor to Lloyd's Register; experiments with models of constant length and form of cross section, but with varying breadths and draughts, by Lieut.-Colonel B. Rota, Royal Italian Navy; experiments upon the effect of water on speed having special reference to destroyers recently built, by Harold Yarrow; deductions from recent and former experiments on influence of the depth of water on speed, by W. W. Marriner; the failure of some large boiler plates, by J. T. Milton, chief engineer surveyor to Lloyd's Register; a comparison of the performances of turbines and reciprocating engines in Midland Railway Company's steamers, by William Gray.
It was also arranged that visits should be paid to the following works:-Siemens Bros. and Co.'s Telegraph and Electrical Instrument Works, near Woolwich ; Vickers, Sons and Maxim Ordnance Works, Erith; J. and E.
Hall's Refrigerating Machinery Works, Dartford; Yarrow and Co.'s ship-building yard and marine engine works, Poplar; John I. Thornycroft and Co.'s ship-building yard, marine engine works, and motor-car works, Chiswick. Visits were also paid to the P. and O. mail steamer India, lying in the Tilbury Docks, and H.M.S. Black Prince, built by the Thames Iron Works, and lying in the Victoria Docks. The last day of the meeting, Dockyard. Friday, July 21, was occupied by a visit to Portsmouth
The first sitting during the meeting, when the three first papers on the list were presented, was held on Wednesday, July 19, the president of the institution, the Right Hon. the Earl of Glasgow, occupying the chair. These papers, as will be gathered by the titles, were chiefly of historical interest. In this centennial year of Trafalgar it was, no doubt, appropriate for the institution, which is so largely naval in its composition, to include in its programme papers of the nature of those contributed by Sir Cyprian Bridge and Sir Philip Watts; but how far they have any scientific bearing on naval strategy or tactics of the present day is a question that is evidently open to discussion. It would appear that a large section of naval officers hold that the lessons of the past era of masts and sails should be applied with little modification
to the present day. For example, Admiral Sir Edmund Fremantle said that the tactics and strategy at the time of Trafalgar taught lessons which would never die, and Admiral Custance remarked that all the lessons of the past in naval warfare have a bearing on the present day, it being quite immaterial whether vessels were moved by steam or sail. On the other hand, there are some who hold that the disciples of what has been described as the teachings-of-history school carry their reverence for the past to an excessive degree, and that a too blind following of the tactics and strategy of the great admirals of the past may lead to disaster. Sir Philip Watts, in the course of his paper, pointed out that steam propulsion, in all its various forms, shell fire, iron and steel armour, steel hulls, breech-loading and rifled guns, torpedoes, mines, high explosives, electrical appliances, and submarines have all been introduced since the day of Trafalgar; and though he did not press any moral from these changes, his predecessor at the Admiralty was a little more explicit, as it was possible for one no longer trammelled by the rules or etiquette of office to be. Sir William White said in the discussion that while he agreed with Sir Cyprian Bridge that the teachings of history were valuable, it was necessary to allow for changes brought about by time. He did not think such a course was followed on all occasions.
Mr. Cornish's paper, as a record of the past by a competent authority, is one which should prove of considerable value to the student and historian of ship-building. The author did not urge its reading as time was short, and it was accordingly taken as read.
Colonel Rota's paper was the first taken at the evening sitting of Wednesday, July 19. It formed but a part of a very big subject, and was in the nature of an addition to Mr. R. E. Froude's paper on model experiments, read last year. The experiments briefly described by Colonel Rota were made with five models at the Royal Italian Dockyard, Spezia. It would be difficult to give the results of the inquiry without going into the whole question, but it may be stated that the author, without attempting to draw any general deduction, has practically concluded that in the unlimited series of forms which may be derived from a given form of hull by changing the vertical and horizontal cross sections scale-provided that the area of cross sections remains constant-there is a range of ratio of beam to draught, very close to that corresponding to the least wetted surface, within the limits of which there is not any sensible variation in the value of the resistance constant, that is, the corresponding E.H.P. There was no discussion on this paper, but Sir William White had written to Mr. Dana, the secretary, endorsing the author's plea for the publication of results of a purely scientific nature.
The two papers contributed respectively by Mr. Harold Yarrow and Mr. W. W. Marriner were no doubt the chief attraction during the meeting, and the little theatre of the Society of Arts was crowded to its full capacity by those anxious to benefit by the investigations carried out by Messrs. Yarrow and Co. Both papers referred to the same experiments, the authors having been engaged together on the work. Mr. Marriner, as is well known, is the chief of Messrs. Yarrow's scientific staff, whilst Mr. Harold Yarrow is still a student of the institution, and it is worth noting that his paper is the first contribution to the Transactions by a student. The data given possesses the merit of being both of scientific and practical interest. It has for some time past been recognised that depth of water has a considerable influence on the speed of steam ships, and Government contractors have lost considerable sums of money through failure to attain speed on the official measured miles. The scientific interest of the subject is unlimited, the problem involving the study of the natural laws governing wave-making and fluid resistance. It is to be hoped that ship builders and ship owners now they have had placed before them so striking an example of the value of scientific research upon the practical results at which they aim-will do something tangible to help forward an inquiry into the influence of physical laws upon the resistance of vessels progressing in water. It is not creditable to the ship owners and ship builders that they should be beholden to the generosity of
a private firm of torpedo-boat builders for information on these points, especially as such information cannot be obtained without the expenditure of several hundreds of pounds. The exclusive knowledge of the facts set forth in the two papers would prove a valuable asset to Messrs. Yarrow and Co. by giving them a distinct advantage over their competitors, and it is therefore more creditable to them that they have made the details public. It is, however, the greatest reproach of all to us, as the leading maritime nation, that Mr. Yarrow should have been under obligation to a German ship-owning firm for the facilities needed to make the investigation complete. Had it not been for the hospitality of their experimental tank offered by the North German Lloyd Company, the valuable information now at the command of ship designers would not have been forthcoming, for there is no tank of the same nature in this country which could have been used.
The experiments upon which the two papers were founded arose through Messrs. Yarrow and Co. having failed to get the contract speed of 25 knots with destroyers built for the Royal Navy when they were tried on the Maplin mile off the mouth of the Thames. The builders, anticipating that the limitation in depth of water was accountable for the want of success, surveyed on their own account a mile near Dover, the section posts being placed on the cliffs. Here, in a greater depth of water -50 feet at low tide the contract speed was reached, the vessels running a great part of the time in quite deep water outside the Goodwins. It should be explained that the trials last over four hours, and only six runs are made on the measured mile. On these six runs is found the number of revolutions needed to cover a mile, and then by counting the revolutions the distance steamed can be known. Although the contract was fulfilled, the results were not altogether satisfactory to the contractors, and Mr. Yarrow determined to have tank experiments made, testing a model of the destroyer at depths corresponding to 20 feet, 30 feet, 45 feet, 60 feet, and 90 feet respectively. The results were shown by diagrams thrown on the screen by the lantern, there being curves for speeds and for effective horse-power at the above depths. The results were somewhat remarkable. Each curve showed a distinct hump, indicating that when a certain speed was reached the power needed for an increased speed rose with enormous rapidity. This, of course, was in accordance with previous experience, and it was also to be expected, as shown by the diagram, that the hump would occur at lower speeds with shallower water; thus at 20 feet depth the top of the hump was at about 16 knots, at 45 feet it was about 20 to 21 knots, and at go feet the steepest part was from 20 to 24 knots. As the depth increased the curve became fairer.
The interesting feature brought out, however, was the fact that at a certain speed, depending on the depth of water, for a time the power decreased as the speed advanced. Thus in a depth of 20 feet, at a speed of about 15 knots, 2000 horse-power was needed; when the speed had been increased by approximately another knot the power developed was about the same, whilst at 17 knots the demand for power had fallen off appreciably, and it was not until 18 knots was reached that the 2000 horsepower was again required, and after this the curve rose steadily. With a depth of 30 feet the descent of the curve was even more marked, about 2500 horse-power being needed for approximately 17 knots and for 20 knots also. Comparing the powers required for speeds at different depths, we find also some remarkable results. At 18 knots 2500 horse-power was needed when the water was 30 feet deep, whilst when it was but 20 feet only 2000 horsepower had to be developed to reach the same speed, thus reversing the popular idea that the deeper the water the easier the boat would run. Again, at 20 knots, and when the water was 20 feet (and also when the depth was about 30 feet-the two curves approximately coinciding here), 2500 horse-power was needed, but to get the same speed with a depth of 45 feet about 315 horse-power was needed. Passing at once to the higher speed of 26 knots, we find that the highest power is needed when the beat is steaming in deepest water. After crossing and re-crossing each other, the curves for four depths (20 feet, 30 feet, 45 feet, and 60 feet) come fairly well together, having got