photometers of the Bunsen type are to be preferred to those of the flicker type. He considers the latter, although more sensitive than the former, give readings for the comparative brightness of the two lamps about 6 per cent. from the true value. He finds photometers of the Lummer type come short of the Bunsen in sensitiveness, and he thinks that in time the Bunsen will displace the other photometers at present in use. BULLETIN No. 30 of the University of Illinois consists of an important paper, by Mr. J. K. Clement, on the rate of formation of carbon monoxide in gas producers. The numerous theoretical works on the processes taking place in the fuel bed of the producer have been built up on a rather slender experimental basis, and the present communication fills a decided gap in our knowledge. The experiments deal more especially with the rate of formation of CO in the reaction CO2+C=2CO, previous researches having been rather directed to the study of the final equilibrium than to the rate at which the reaction takes place. Three authors contribute to this memoir, J. K. Clement, L. H. Adams, and C. N. Haskins, dealing with the subject from the physical, chemical, and mathematical point of view respectively. The result of this collaboration is a valuable monograph, which cannot be neglected by anyone interested in gas producers. MR. W. B. CLIVE has published a second edition of Mr. William Hall's "Modern Navigation." The text-book deals also with nautical astronomy, and is intended to meet the needs of cadets of the Royal Navy and the syllabus of the Board of Education. The scope of the volume is limited to instruction in navigation so far as, and including, the problem of fixing position by one position line derived from sights of the sun and another derived from a bearing of land. The book has been entirely re-cast. Its price is 7s. 6d. to AN abstract of Dr.. John Morrow's contribution part iii. of the third volume of the Proceedings of the University of Durham Philosophical Society was published in NATURE of July 29 (vol. lxxxi., p. 128). The volume contains, in addition, other articles of interest, among which the following may be mentioned :-Prof. Thornton describes a new method of measuring v; Prof. G. H. Stanley contributes a note on an artificial formation of zincite; Dr. D. Woolacott writes on borings at Derwenthaugh and Dunston; Mr. A. S. Horne describes observations on protoplasmic structure and streaming in potato; Messrs. Harold Crofts, H. Tiplady, and A. Forster discuss certain chemical experiments; and Messrs. T. Herdman and E. Merrick record observations in local geology. The third report of the Boulders Committee is also included in the volume. OUR ASTRONOMICAL COLUMN. MOVEMENTS IN THE SUN'S UPPER ATMOSPHERE.-In continuation of his previous papers, giving the results of the solar researches carried on at Meudon, M. Deslandres has a paper in No. 3 of the Comptes rendus (p. 179, July 19) wherein he describes and discusses more recent results dealing with the question of motion in the upper layers of the solar atmosphere. First he mentions the connections previously shown to exist between spots, 'filaments," and alignements,' and points out that owing to the greater size, frequency, and distribution of the latter, they afford much more trustworthy and continuous data on which to base any researches or theories dealing with solar changes than does the study of spots alone; but for any exhaustive study of these phenomena the velocities of the solar vapours in the line of sight must be determined, and it is to this determination that M. Deslandres has in the more recent work returned. 66 As To measure the radial velocities all over the disc would take much more time than the Meudon staff are able to devote to the work, so, for the present, only those in the neighbourhood of filaments near the centre of the disc have been measured. A diagram of a typical radial. velocity curve shows that in the filament, shown on the K," image, the vapours are moving towards the observer, the displacement of the line being towards the violet. At first glance this appears to contradict M. Deslandres's previous conclusions, and the fact that whilst, in May and June, when spots were scarce, or small, the filaments were well developed, yet further suggests that the two phenomena are not physically connected; but M. Deslandres thinks it necessary only to modify and enlarge these conclusions, and shows how solar convection currents, analogous to Benard's cellular liquid tourbillons, would account for the apparent discrepancy of the results, and, at the same time, afford an explanation of Evershed's radial motions observed in the penumbræ of spots. SEARCH-EPHEMERIDES FOR COMET 1896 VII. (PERRINE).— Ristenpart publishes a set of elements, brought up to the In No. 4342 of the Astronomische Nachrichten Herr F. W. equinox of 1910, for the comet discovered by Perrine in 1896; the time of the next perihelion passage is given as 1909 November 4.12 (M.T. Berlin). Three searchephemerides, computed from the elements by Messrs. R. Castro and A. Repenning, are also given, T being taken as October 27.5, November 4.5, and November 12.5 respectively. According to the second ephemeris, the comet is at present in Pegasus (August 6, 12h. M.T. Berlin, a=23h. 44.2m., 8=+31° 40.2'), and will apparently travel, in a north-easterly direction, through Andromeda towards Perseus on August 24 its position should be a=oh. 11.4m., 8=+40° 12.4', and the comet should appear about as bright as when discovered. The computed brightnesses at perihelion are 6, 13, and 20.5 respectively, according to the date of perihelion passage. OBSERVATIONS OF JUPITER.-Some incidental measures of the positions of Jupiter's belts and of the polar diameter of the planet are given by Prof. Barnard in No. 4339 of the Astronomische Nachrichten (pp. 307-10). For each recognisable feature he gives the distances from the south and north limbs and the apparent latitude; the observation on February 19 8h. om. (central standard time), 1907, gave the apparent polar diameter as 40.78", and, reducing this to A=5.20, the polar diameter therefore becomes 36.11". On this date a narrow south belt, 2" wide, in apparent latitude -9.88", showed several ill-defined white spots, and on May 26, 1908, the north equatorial belt was double for part of its length. THE ORBIT OF X SAGITTARII, A CEPHEID VARIABLE.The variability of the star X Sagittarii was discovered by Slipher in 1904. Schmidt in 1886, and the radial velocity detected by In No. 157 of the Lick Observatory Bulletins Mr. J. H. Moore discusses a series of oneprism and three-prism spectrograms taken at Mount Hamilton during the period 1904-8. Plotting the velocityand the light-curves for the same epoch, it is shown that the times of light-maximum and of greatest velocity of approach agree very closely, this being a fundamental characteristic, as Mr. Albrecht has shown, of all variables of the Cephei type. No such close agreement is shown, however, between the epochs of light-minima and maximum recession. THE LEEDS ASTRONOMICAL SOCIETY.-The energy and activity of the Leeds Astronomical Society in popularising the study of astronomy is well illustrated in the Journal and Transactions for 1908. This journal contains abstracts of the papers read before the society, and a large number of astronomical notes contributed to various periodicals by Among the former there appear papers on sundials (Mr. Messrs. Elgie and Whitmell, members of the committee. T. Wright), variable stars (Mr. Ivo Gregg), and "other inhabited worlds" (Mr. T. Benton), while an interesting popular paper dealing with the fancied figures in the moon is contributed by Mr. Elgie. THE SOLAR ECLIPSE OF JUNE 17, 1909.-Observations of the contacts, during the solar eclipse of June 17, were made by Father Rigge, at the Creighton University Observatory, Omaha, and showed that the phenomena actually occurred a second or two earlier than the computed times. At first contact the difference was 2.02s., and is trustworthy, but at the last contact a difference of 18.4s. was observed, and may largely be due to the extremely bad conditions under which the observation was made, the sun being within fourteen minutes of setting (Astronomische Nachrichten, No. 4340). RECENT IMPROVEMENTS IN THE INTERNALCOMBUSTION ENGINE. I. A SURVEY of the progress made during the last twentyfive years in almost any field of engineering work would show an immense advance. Even during the past ten years very considerable progress has been made in certain branches of applied science, and in none of them to a greater extent than in the internal-combustion engine. We need not in this comparison claim the gun as a form of internal-combustion engine, though we are naturally entitled to do so. We may leave lethal weapons aside, and think only of the remarkable development of the reciprocating internal-combustion engine, and of the many changes it has brought about in our times. It has revolutionised cross-country transit. It has given us the longdeferred, but now actually achieved, victory called the conquest of the air." It is extraordinary to think of the numbers of men who have spent ingenious years in seeking a solution of the problem of flight. The solution has come in the unexpected form of a pair of long, sail-like arms, driven forward by a small high-speed internal-combustion engine. This simple form of design, which, owing to the relation between centre of pressure and angle of tilt, seems to be naturally stable, bids fair to be adopted in a great output of flying machines shortly to be constructed. The hardly less novel, but less interesting, dirigible balloon Owes the whole of its dirigibility, whatever that may amount to, to the internal-combustion engine. Less startling, but of considerable material importance, is the utilisation of "waste heat" in our coal- and ironproducing areas. Our coal supply is admitted to be limited, and there seems to be at least an indication that at the present rate of consumption mankind would, in a few centuries, have to be prepared to turn its attention to the unlocking of some other form of stored-up energy, perhaps a radio-active one. It is not too much to say, however, that if the power available from the waste gases of blastfurnaces and coke-ovens in this country-and the amount can hardly be less in the aggregate than 1,000,000 h.p.were put to use, the saving in the coal consumption might perhaps give us another half-century or two in which to look about for some substitute for coal. In writing of what has been already achieved, we have to remember that we are only yet at an intermediate stage in the development of the internal-combustion engine. The internal-combustion engine gives us a bigger return for heat put in than any other known form of engine. We cannot imagine the development of the future " going back," so to speak, on such an advance as that. The internal-combustion engine must come, and existing steam engines be replaced. This means the supersession of the steam turbine, and may therefore seem to suggest a retrograde step, since the rotary engine is mechanically an improvement on the reciprocating one. We have to remember, however, that evolutionary processes sometimes take a step backwards to an earlier form in bringing forward the latest and most developed creation. No one would look on any reciprocating engine as a final improvement on a rotary one, even although, as is now the case, large gas engines are capable of so uniform a rotary motion that alternators are easily driven by them in parallel-the standard test of excellence in this respect. The day of the gas-engine turbine must come. Numbers of men are working at the problem which it presents; but little has as yet been published as to the result of their labours-an indication that the many difficulties are not yet mastered. The present stage in the development of the internalcombustion engine is a convenient one at which to summarise briefly what has been done in regard to itsimprovement. We therefore propose in this and the succeeding articles of the series to state the problem and the lines on which, with such a striking measure of success, its solution has been attempted. The problem can be stated in a very simple form. Given one pound of carbon of, say, 12,000,000 ft. lb. calorific value, which is a normal estimate, find how to obtain the largest possible amount of useful power. So far thisenergy has always been liberated in the form of heat. This heat has been given to some body which, by its subsequent cooling, can give out mechanical energy-such a body is a mass of gas or vapour. Let us assume that a mass of gas is chosen as the working medium. It is obviously desirable that the heat liberated should be absorbed as completely as possible by the gas, but in investigating whether this has been effected one at once meets with a check. To tell whether the whole of the 12,000,000 ft. lb. of heat energy has reached the gas, we may either look out for possible chances of heat leakage or may measure the amount of energy in the gas at the end of the operation. But to do the latter is practically impossible, for we do not know the specific heat at high temperature of any gas, and to do the former is extremely difficult, owing to the very short time the heat transference usually takes, and owing also to our lack of knowledge as to the temperature of metal or other surfaces in contact with, and enclosing, the gas. Many attempts have been made to ascertain what happens to the heat liberated, and much has been written on such topics as dissociation,' after-burning," and "increasing specific heats." There would be no difficulty in filling the whole of the allotted space with a discussion of the various experiments that have been made and theories that have been built on this subject, but as many other matters have also to be dealt with, and as the author has already written on this topic elsewhere,' he does not now propose to gointo the matter at length. Briefly summarised, the result of gas-engine experiment is to establish that only about 50 to 55 per cent. of the heat energy known to be liberated is accounted for by multiplying the measured rise of temperature by the commonly accepted figure for the specific heat at constant volume. The same ratio of 50 to 55 per cent. was found for all sizes and shapes of containing vessel, and for all mixtures of gas. This constancy at once disposed of the theory that the "suppression of heat" was due to dissociation, as such an effect would naturally be dependent upon, and increase with, the increasing temperatures due to the richer mixtures. Equally it showed that the cooling of the gas by convection currents, radiation, and conduction to the walls of the containing vessel was an inadequate explanation. The suggestion of the French physicists, MM. Mallard and Le Chatelier, that the effect must be due to increase of specific heat with temperature was open to precisely the same objection as that of dissociation, and involved values of the instantaneous specific heat much in advance of what was then thought likely. It is now generally rcognised that the real explanation of the apparent suppression of energy is due to a combined cooling effect and rise of specific heat. After-burning" is now generally believed, as a result of many tests, not to occur in normal circumstances. With a weak mixture the time of explosion, and therefore of cooling, is a long one, so that the cooling loss has time to become considerable, and this compensates for the lesser degree to which the theory of increasing specific heats is effective for these weak mixtures and low temperatures. The constancy of this apparent "loss" made it clear that no great improvement in the internal-combustion engine could be looked for in any increase of pressure and temperature in a gaseous mixture of given strength. We cannot alter the specific heat law of a substance. We might, perhaps, alter our working medium, which now for the most part is nitrogen, but no other gas is so cheap or so easily obtained; but we may vary the part of the temperature scale over which we work, and, within limits, we may affect the cooling loss by altering the shape of the containing vessel or cylinder. Experiments have shown 1 "The Internal-combustion Engine" (Constable and Co.) that the less the ratio of cooling surface to volume the less the proportionate cooling loss, and therefore the greater the amount of thermal energy converted into work. Engines that have "pockets," that is, cavities in their walls, in which to contain ignition plugs or valves, are known to be less efficient than those that have not. On the other hand, it must not be forgotten that although this loss of efficiency exists, it is at any rate partly compensated for by the greater flexibility of the engine. It has been found, particularly in motor-car engines, that pockets" have a very useful effect in enabling very variable mixtures to fire. The ignition plug is placed in a pocket so that, even when the mixture is a very poor one, there will be sufficient local richness in its neighbourhood to start an explosion which, once started, proceeds throughout the mass of the gas. Another fact which may have the result of increasing "pocketing" is the recently measured temperature limit for preignition. Prof. Hopkinson has found that surfaces below 700° C. will not cause pre-ignition, whilst those above may do so-if above 750° C. they are pretty sure to do so. Now the surfaces most likely to rise to such temperatures are those remote from the cooling water in the jacket. The projecting end of an ignition plug is such a surface, and when exposed to the full heat of the explosion, as it is when the plug is not pocketed, pre-ignition may well occur. Prof. Hopkinson has shown also that when once a point of metal gets hot enough to cause pre-ignition, the very ignition of the flame in its neighbourhood will tend to cause the temperature to rise still higher, so that the phenomenon grows on itself and persists. It is not everyone who is moved, however, by such considerations, and we have lately seen in the design of the new Daimler engine a clearly expressed intention to avoid pocketing and its consequent loss of efficiency without any apparent fear of introducing other features much less desirable. It is only fair to say, however, that this engine is still on its trial. The ideal plan would appear to be to pocket the ignition plug but not the valves, and so combine the good features of both systems. This frank abandonment of the highest possible efficiency by those who use pocketed engines brings us naturally to the consideration of thermal efficiency and the laws that regulate it. One may say at once that the theory of the internal-combustion engine has, until lately, been in a chaotic condition. The standard of efficiency for gas engines laid down by an influential committee had been found subsequently to be unsatisfactory as giving an impossibly ideal figure. That such remarkable progress in invention and mechanical perfection should have gone on side by side with this uncertainty as to the true standard of perform ance has often struck observers with astonishment. The considerable scale of the practical side of gas-engine development is illustrated by the fact that of one wellknown make of double-acting gas engines alone, no fewer than 247 engines of an aggregate output of 308,000 b.h.p. have been built or ordered during the last six years. This corresponds to the large figure of more than 50,000 b.h.p. per year for only one of the many firms engaged on the work. At the moment the total capacity of gas engines in use must be well over 2,000,000 h.p., and of petrol engines much more than 1,000,000 h.p., making a total of more than 3,000,000 h.p. in internal-combustion engines. These are striking figures. Some of these engines and plants work with solid fuel and some with liquid. It would not be possible, even were it considered desirable, to use liquid fuel to the entire exclusion of any other. The present output of petroleum over the whole world is only 20,000,000 tons, a very small figure compared with the yearly consumption of 800,000,000 tons of coal. Unless, therefore, fresh supplies of oil are discovered, there can be no development of the internal-combustion engine which would lead to liquid fuel replacing solid fuel altogether. In the articles that will follow. the author intends to deal with the problem of efficiency, taking into account the now established increase of specific heat with temperature, its effect on rating, and the recent practical improvements in the design and operation of gas engines and gas-producing plant. H. E. WIMPERIS. CONTINUATION SCHOOLS AND NATIONAL AMONG EFFICIENCY.1 the numerous problems now confronting English educational administrators, probably the most urgent is that discussed in the valuable and exhaustive report on attendance at continuation schools recently issued by the Consultative Committee of the Board of Education. To some extent the report covers age Under these conditions the education, such as it is, given in the elementary school is being rapidly forgotten. The boys and girls are almost entirely exempt from parental control; they are falling victims to the prevailing passion for cheap amusements and to the attractions of the streets. Any slight gleam of intellectual aspiration which may have been aroused in the elementary school is rapidly being extinguished. The enormous sums spent by the State upon the elementary education of these young people are almost entirely wasted. All that remains is a certain facility in reading, writing, and very elementary arithmetic. Even if the boys are definitely apprenticed to a trade, matters are not much better. Under the present industrial conditions, involving the minutest possible specialisation in the works, the employer cannot possibly afford, even if he wishes, to give the boy the all-round training which was given by apprenticeship under the older industrial régime. Industry now requires, in addition to manual dexterity, a general industrial knowledge and a trained intelligence which will enable the worker to adapt himself to ever-changing industrial conditions; but this knowledge and training are not now given by apprenticeship. Hence, an education outside, but concurrent with, the workshop is essential. A further important factor is that even if a boy be apprenticed to a skilled trade, he is generally not taken on until about sixteen years of age. The intermediate years, between leaving school at thirteen and commencing apprenticeship at sixteen, are usually spent in "blind alley," uneducational occupations such as that of errand boy, van boy, messenger, &c. For many years to come the formal education given to the bulk of the population of this country will be that imparted in the elementary school, the continuation evening school, and the evening technical (including by this term commercial, or art or craft) school. The nation, at enormous expense, has instituted a system of national education which is almost entirely confined to children under fourteen years of age. In addition to this, an elaborate system of evening technical education has been established, mainly for those above the age of seventeen; but no adequate national system of evening continuation schools, for the boys or girls between the ages of fourteen and seventeen, linking on the elementary school to the evening technical institution, has yet been developed. The boy or girl leaves the elementary school at the age of thirteen. At seventeen or eighteen the youth may realise the necessity of attending evening classes for technical instruction relating to his special industry, assuming he is engaged in some skilled occupation or other. At the technical school he finds that he is unable to profit by the instruction given. During the years between thirteen and seventeen his powers of assimilation have declined through disuse, he has lost the habit of study, and most of his previous small stock of knowledge, e.g. mathematics and English, has vanished. He speedily becomes disheartened and ceases to attend. As a result, the greater portion of such chances as he possesses of rising in his trade, or of even keeping his position in a few years' time, vanishes. Not only is the worker thus damaged in an industrial sense, but the community loses, first by his diminished efficiency as an industrial unit, and secondly by the lessening in the sum total of sustained intellectual effort made by its citizens. Every workman, who by systematic instruction passes from the level of the ordinary artisan to that of the trained, intelligent worker, becomes an asset of increased value to the nation. The problem now is, What can be done to (a) carry on the education of the wage-earning youth of this country during the years from thirteen to seventeen, (b) bridge over the present gap between the elementary school and the centres of higher evening instruction, such as the technical school? The solution lies in the development and the increased efficiency of the evening continuation school. The following statistics for 1906-7 from the report are not without interest as showing to some extent the measure of success which has been obtained : : Percentage of evening five years In recent years special attempts have been made in some districts to persuade boys and girls on leaving the elementary schools to join the continuation schools without delay. Some striking results have been obtained. In Widnes about 80 per cent. of the boys leaving the elementary schools commence attendance at evening schools without a break. Halifax has secured 66 per cent. Lancashire County Education Committee reported in The January that in the larger boroughs 37 per cent., and in the smaller boroughs 22 per cent., of the boys and girls leaving school during the year ending October 30, 1908, the evening employment, joined to secure immediately. schools The principal recommendations of the Consultative Committee are the following: (1) The leaving age should be raised to thirteen years, and after a short period to fourteen years. (2) Full-time exemption from the day school should only be given to boys and girls under sixteen when the parents or guardians can show that the children in question are suitably employed. (3) It should be the statutory duty of each local education authority to make suitable provision of continuation classes for the further education of young persons up to the age of seventeen. (4) Local education authorities should be empowered to at continuation make bye-laws compelling attendance classes for young persons up to the age of seventeen, and employers should be compelled to make provision enabling such young persons to attend the continuation classes. under penalty to (5) Employers should be forbidden employ any young person under seventeen years of age attend the evening continuation classes who fails to regularly. (6) The curricula of the continuation schools should be such as to continue the general education given in the primary school. It should have reference to the crafts and industries in the district, and prominence should be given to practical and manual instruction. Most educationists will heartily support the above recommendations. Numbers (3) and (4) of the above are taken from the Scotch Education Act of 1908. The committee points out that in Germany attendance at continuation schools is compulsory in portions of twenty-two out of twenty-six of the constituent States of the Empire, and in Switzerland in portions of nineteen out of the twentyfive cantons of the Republic. The committee is of opinion that there is now a strong and rapidly increasing body of public opinion ready to support its recommendations. The committee estimates that the total cost (imperial and local) of "maintenance" which would follow from raising the leaving age to fourteen would be about 490,00ol. per annum. The corresponding cost of compulsory continuation classes (exclusive of new buildings) would be about 2,600,000l. per annum. The proposals of the committee, if adopted, would have important educational and sociological results. Thus for example, one of the main causes of unemployment would be eliminated. Educationally the proposals would have a far-reaching effect upon the development of a complete national been before system of education. As has indicated, the continuation schools would take the boys and girls from the elementary schools, continuing without a break their general education, while specialising to a limited extent in either commercial, agricultural, technical, or domestic work, depending upon the requirements of the pupils. At the age of seventeen the boys and girls, after this preliminary training, could then be drafted on to technical, or commercial or art schools. The continuation schools would thus link on directly, and coordinate with, the elementary schools on the one hand and the technical institutions on the other. The direct and indirect gain to the community from (a) the improvement of the general education of the masses, (b) the increased technical efficiency of the workers, would be incalculable. In this connection the following extracts from the report may be given : "An increasing stock of practical ability in a nation enlarges the range of its economic abilities and rapidly adds, through all the gradations of directive responsibility. to the number of well-remunerated posts which could never have existed if men had not been forthcoming to fill them." "A rising level of education among the mass of workers increases the real level of their wages, though this mav not be accompanied by a rise in their nominal amount. It conduces to wise expenditure of income and to the avoidance of thoughtless or harmful waste. Improvements in educational opportunity make possible phase when the fish is at rest. Under any excitement, such as the presence of visitors, the fish assumes a parti-coloured aspect. This paper clearly shows how inadequate and misleading are many of the descriptions of colour hitherto accepted, and is a very suggestive and attractive piece of work. An error occurs on p. 3, where it is said that "their different colours result from muscular action upon one or more kinds of cells." The mechanism of colour-change is not muscular, but nervous. MINERAL OUTPUT OF THE UNITED STATES! THE well-known publication referred to below now appears in a form slightly different from the one to which we have hitherto been accustomed, being issued in two volumes, the first devoted to the Metallic products and the second to the Non-metallic products; this is done in consequence of a recent legislative enactment (Act of May 27, 1908), and presents some advantages, though it might be well to submit, with all respect, to the Government of the United States, that these (and sundry other) publications of the United States Geological Survey stand in far greater need of condensation than they do of expansion. When a work becomes unwieldy, there are two obvious remedies, either to issue it in two volumes or to compress the information it conveys into smaller compass; the latter is no doubt the more difficult proceeding, though the one that best serves the interests of the readers, and it is a matter of regret that, in this case, the line of least resistance has been followed. In the present instance it leads also to a few anomalies, as, for instance, the inclusion of crushed steel (as an abrasive) and of certain other metalliferous materials, such as arsenic, manganese, chromite, &c., in the volume devoted to non-metallic products. It is greatly to be regretted that the mineral statistics of the United States are issued in a form that makes comparisons with the mineral output of other nations difficult; for example, the various values of the metals are reported, not in the form of ore, but in the metallic state, though obviously the value in this form includes the cost of reduction of the metal, and leads to very serious duplication, which the compilers appear to have overlooked, although the introduction lays stress on the statement that "all unnecessary duplication has been excluded." To take an example, the production of iron ore is not given, but instead of it that of the pig-iron smelted from it, namely, nearly 26 million tons, valued at about 530 million dollars. Now the production of coke for the same year was 40 million tons, produced from 62 million tons of coal, valued at nearly 73 million dollars. Practically the whole of the pig-iron produced was made with coke as fuel, and, in the absence of exact figures, it will probably be a near approximation to the truth if we assume that three-fourths of the coke production, or, say, 30 million tons, was consumed in the production of the above pig-iron, so that coal to the value of, say, 55 million dollars was utilised in this way, and this sum is accordingly included in the above valuation of the pig-iron production; it is, however, also included in the sum total of the value of the coal production, and thus enters twice Two Colour-phases of the Nassau Grouper (Epinephelus striatus). conditions in the aquarium of the society. The changes of coloration "begin to be in evidence within an hour of the arrival of new specimens, or as soon as they recover from the alarm produced by handling, and are produced as long as the fishes live in the tanks, which, in some cases, may be several years." The phases of coloration are illustrated by a striking series of photographs, two of which are reproduced. From these it will be seen that the fish can pass from a uniformly dark (plumbeous) colour to a banded phase with white markings. Four other phases can also be assumed, including a uniformly creamy-white one. This plasticity of coloration is characteristic of most of the fish dealt with, which include Serranidæ, Scaridæ, Teuthididæ, and Scorpænidæ. There is frequently a pale and a dark monochrome 1 Mineral Resources of the United States, Calendar Year 1907. Part I.. Metallic Products. Pp. 743. Part II.. Non-metallic Products. Pp. 897. (Washington: Government Printing Office, 1908.) |