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Office: St. Martin's Street, London, W.C. Knowledge. With which is incorporated Hardwiclte's Science Gossip, and the Illustrated Scientific News. A Monthly Record of Science. Conducted by Wilfred Mark Webb, F.L.S., and E. S. Grew, M.A. MARCH, 1915. CHAPTERS IN SPECTRUM ANALYSIS. By W. MARSHALL WATTS, D.Sc. L — Law and Order in Spectra. A. Line Spectra. (Continued from page 37.) Series in line spectra, similar to that of hydrogen represented in Balmer's law, are found in many spectra, such regularities being the rule and not the exception. The most extensive of such series is that observed in sodium, and known as the Principal Series. The well-known yellow lines seen in the spectrum of a sodium flame constitute the first term of this series — the double hne {sQno.iof- The second term of the series is the double line and no /3303-07\ ^, .K- . . ■ /2853-041 \3302-47/ '• ^^^ ^^'^ *^™ ^' 12852-84/ doubt all the other terms are double also, though the pairs may be too close to be separated. It is well known that the sodium lines are easily reversed, being then seen as dark lines, e.g., the Fraunhofer lines Dj and D.^ in the solar spectrum ; and Professor Wood, by observing the absorption spectrum of sodium vaporised in an iron tube heated to a dull red-heat, has extended this series of lines from the seven terms previously known in the laboratory to no fewer than forty-eight terms. This extensive series is represented in the diagram (see Figure 60). It is a question of much interest to examine whether the wonderful " law and order " exhibited by the hydrogen spectrum, and shown by the exact agreement of the observed wave-lengths with those calculated from Balmer's formula, can be traced in this still more extended series. We see that the case is now somewhat less simple than with hydrogen. In the first place, we have now to deal with a series of double lines, or rather with two series of single Unes ending at the same convergence- frequency, since the Hues of the pairs become closer and closer together as we pass from red towards blue. In the next place, we soon find that the law of the series is not so simple as that of the hydrogen series, and therefore requires a more complicated formula for its expression. The most satisfactory formula appears to be that employed by Mogendorff in 1906, and by Hicks in 1910, namely, O.F, = C,F.- '°*'5 ("■ + '' + ^) Balmer's formula for hydrogen, it will be remembered, is a simpler form of this, namelv, ^^ ^^ 109675 O.F. = C.F.--^ in which m is put equal to 1,2, 3, and so on, suc- cessively, and n and c are constants. Since we have to deal with pairs of lines, we must have two formulae, one for the less refrangible and the other for the more refrangible lines of the pairs. The best values of the constants are : — For the less refrangible hne : ^ = 0-U7408. c= -031328. For the more refrangible line : ^ = 0-148204. c= -031380. The convergence - frequency, C.F., has the same value for both components, namely, 41 448-67. The 65 66 KNOWLEDGE March. 1915. "alues a° shown in the follo^ving table . The Prktcipai^SekiesjnJodium { ( 5896-16 5890-19 / 3303-07 \ 3302-47 2852-93 2852-84 2680-46 2593-98 2543-82 2512-15 2490-70 2475-60 2464-53 2456-02 2449-46 2444-24 2440-06 2436-70 2433-85 2431 -43 2429-42 2427-72 2426-28 2425-00 2423-88 2422-90 2422-04 2421-29 2420-60 2420-02 2419-50 2419-00 2418-44 2418-09 2417-71 2417-38 2417-10 2416-80 2416-56 2416-33 2416-11 2415-89 2415-70 2415-52 2415-37 2415-21 2415-06 2414-94 2414-78 2414-64 2414-50 5896-16 \ 5890-19/ 3303-07 \ 3302-47 / 2853 04 \ 2852-84 / 2680-39 2593-89 2543-86 2512-16 2490-74 2475-56 2464-42 2455-97 2449-42 2444-23 2440-06 2436-64 2433-82 2431-45 2429-44 2427-73 2426-26 2424-99 2423-88 2422-90 2422-04 2421-29 2420-59 2420-00 2419-45 2418-96 2418-51 2418-11 2417-74 2417-40 2417-09 2416-81 2416-55 2416-31 2416-09 2415-88 2415-69 2415-50 2415-35 2415-19 2415-05 2414-91 2414-79 2414-67 2414-56 Bevan. by foUo^g Wood, jnethod, has found l;^ S^r^^PO^o" hK t W^t a,.aU Figure 60. calculated Jh' »TSSSraclacVTr?,n the Mo.endo* Hicks formula : 1 09675 ^007564^ w — 1 ' O.F. = 43482-61 - Ln _ -048596 as shown in the following table : 6708-1 3232-80 2741-44 2562-60 2475-13 2422-55 2394-54 2373-9 2359-4 2348-5 2340-5 2334-3 2329-0 2325-2 2321-9 2319-3 23171 2315-2 2313-6 2312-2 2311-1 2310-0 2309-0 2308-3 2307 -5 2307 -0 2306-5 Calculated. C. 6708-14 3232-81 2741-40 2562-56 2475-27 2425-65 2394-59 2373-79 2359-16 2348-47 2340-41 2334-17 2329 -26 2325-31 2322 10 2319-44 2317-22 2315-34 2313-74 2312-37 2311-18 2310-14 2309-24 2308-43 2307-73 2307 -09 2306-53 «n.ed by a straight I'-J ^^.'^f^^ T horizontal r;foT rr'iag a^'i'^gVen (see F.gure 60) r;s:e^'d"rro.^*Vt^:"ivTco„Unce- frequencies of these elements. • From the formulae OF =41448-67- U + -147408 - lor the less refrangible line, and ^^^^^^ O F = 41448-67 - -. ; :o3T3S\' for the more refrangible component of *^; f ^'' "J^^^rs in the table being mean values. NoxH._After.=4 the two components of the Une are not given separately. March, 1915. .1 1 Kl 1 r /LEDGE. - 1 1 5^^# ^ cy ^ \ Q> Si to t "^ \ \ \ \ L ^ N ^'l \, \ \s. \ N) K> \ \N s o \^ \ \ i \ N [I) \ 1 \ ^^ \ \ o u. \ \ ^% ! \ N ^\ ^"^ ^ \ \ \ ( % \ \ K, ^v \ \ \ •s ^\ j \ \ \ \ \ \ \ ^ \ \ \ V. \ \ K \ \, \ \, "^^^" \ \ > \ -5 5 ^ a = s ) 5 \ I y or 0 ! 5 4 i •♦ 67 68 KNOWLEDGE. March. IQIS. Figure 61. Feather from the tail of a Cock-pheasant. m P! Figure ni- Feather from the tail of the male Pheasant assum- ing female plumage. w^ FiGURii 63. Feather from the tail of a Hen-pheasant. ( the. fpinale now preserveo SX.«U:X5;mDubhn.nl891 Fro,u photographs take, by Messrs. LasccUcs >~ Co, -^- Sfegt S^ur ^J'r S^^StS- ana on. ved in March, 1915. KNOWLEDGE. 69 It wall be noticed that these curves are of verv similar shape for sodium, potassium, rubidium, and caesium, but the Uthium line curves slightly in the opposite direction to the sodium line. This difference corresponds to the difference of sign in the formula. The straight line on the left, marked hydrogen (principal series), represents a series of three lines in hydrogen observed by Professor Fowler. It is further to be noticed in this diagram that the convergence-frequencies of hydrogen, lithium, sodium, potassium, rubidium, and caesium lie in the order of the atomic weights of these elements, namely, t, 7, 23, 39, 85-45, and 132-81 respectively. [To be continued.) MALE BIRDS WITH FEMALE PLUMAGE. It is not at all an uncommon thing for hen birds, owing to old age or injury, to begin to assume the plumage of the cock, and an interesting case has been described in our columns (see " Knowledge," Volume XXXVI, January, 1913, page 7) of a hen Ostrich which, when its ovaries were removed, developed male plumage entirely. The reverse case, however, is rare. We give here a photo- graph of a stuffed specimen of the Common Pheasant in Eton College Museum, which came from the Millais Collection, in which the tail feathers, though of the length usually found in the male, are coloured and marked like those of the female. Figures 61 to 64 illustrate this point very well. There are also certain feathers on the sides of the bird which, instead of being brilliantly coloured like those of the cock, are sober-hued like those of the hen. \v. m. W. THE ZOOLOGICAL SOCIETY At the scientific meeting of the Zoological Society, held on February 9th, Sir Edmund G. Loder, Bart., F.Z.S., exhibited the tanned skin of a large Capybara (Hydrochoerus hydrochoerus) , which he suggested might be identical with the " pigskin " of commerce, and the skull of a Walrus [Trichechus rosniarus) from Kamschatka, with record tusks. The weight of the skuU and tusks was about forty pounds. The tusks alone weighed twenty-one and a half pounds, and measured thirty-six and a half inches in length, tw^enty-nine and a half inches from outside the gum, and nine and live- eighths inches in girth. Dr. P. Chalmers Mitchell, F.R.S., F.Z.S., Secre- tary to the Society, exhibited preparations of the stomach and intestines of the Open-bill {Anasiomus oscitans), and described the elaborate sifting apparatus in the stomach and the presence of only a single colic coecum. Mr. E. Heron-Allen, F.L.S., F.Z.S., exhibited a series of skiagraphs of Foraminifera, revealing their internal structure without transparent mount- ing or section-cutting, or other interference with the specimens, and illustrating the application of .v-rays to microscopical research. Mr. Guy Aylmer, F.Z.S., exhibited some skins of mammals from Sierra Leone, including those of a Serval [Fclis capensis) and of a Servaline Cat (F. servalina), and stated that a native had brought him two kittens, almost certainly from the same litter, one being spotted like the Serval, and the other obscurely speckled like the Servaline Cat. This he regarded as proof that the differences between the Servals and Servaline Cats are of no systematic importance. Mr. E. G. Boulenger, Curator of Reptiles, read a paper on an Aglyphodont Colubrid Snake [Xenodon merremii), with a vertically movable maxillary bone. FLORA SELBORNIEXSIS. March, Third Month [Continued). 11th. — The Dandelion is Taraxacum dens-leonis. The Sycamore, as we now spell it, is Acer pseudoplatanus. 12th. — The Furze [Ulex europaeus) is one of the plants that may be found in flower at all times of the year. Dog's Mercury is Mercurialis perennis. Birch is BeftUa alba ; the Wood Laurel, Daphne laureola. The Humble Bee, if it is a species of Bombylius, should be Humble-bee Fly. The names of the other plants mentioned under this date are : Vinca minor ; Alliaria officinalis ; Senecio jacobaea ; Cynoglossum officinalis ; Malva sylvestris, which still stands ; Nepeta glechoma (Ground Ivy) ; Asperula odorata ; and Daphne mezereum. 70 KNOWLEDGE. March. 1915. 13th. — The Ivy-leaved Speedwell is Veronica hederaefolia. The Lesser Celandine is not a Chelidonium, but is Ranunculus ficaria. Wood-sorrel is Oxalis acetoseUa. The frog and toad mentioned will be the common species in each case, namely, Rana tcmporaria and Bufo vulgaris. 14th. — The JMarsh Marigold is Caltha palustris. The Violets are Viola odorata, and the Meadow- sweet, Spiraea ulmaria. 15th. — Chrysanthemum partheniuin is the name by which the Feverfew now goes. The Larch is Larix europaea. 17th. — The Guelder Rose is Vihurum opidus, and the Coltsfoot, Tussilago farfara. Gilbert White is careful to add after his supposed record of the tuberous Moschatel that the plant was Sanicle, Sanicula europaea. The Pig-nut is Carum hulhocastanum. 19th. — The Wych-elm is Ulnius montana. Soapwort is Saponaria officinalis. The Sloe we now know as Primus communis. The Butcher's Broom is Ruscus aculeatus, and the Wood-ant, Formica rufa. 21st. — Ulmus campestris is the name which is now used for the Common Elm. 28th. — The Hazel is Corylus avellana. THE HISTORY OF THE SCOTTISH SHALE OIL INDUSTRY. By S. C. BRADFORD, B.Sc. Most of the oil fuel now used for naval purposes comes from Russia, America, or Canada ; but it is not generally known that a certain proportion is produced by the destructive distillation of bituminous shale in Scotland, nor that the first paraffin oil to be used on any considerable scale for lighting purposes came from the same source. With the eventual exhaustion of petroleum springs, this method will necessarily be generally adopted, and it is remarkable that in a textbook on liquid fuel, only just published, no mention is made of the subject. As early as 1781 Lord Dundonald showed how to prepare oil from bituminous shale, but no attention was paid to his work ; and it was not until 1830 that Reichenbach discovered solid paraffin. In 1839 the manufacture of the latter was attempted in France by Sellique, who six years later proposed a method for making it into candles. There was, however, no demand for the products, and solid paraffin remained little more than a laboratory curiosity, until, in 1850, James Young took out his first patent for the low-temperature distillation of coal, from which time the history of the Scottish shale oil industry may justly be said to date. Two years previously Young had started a works for refining the petroleum from a spring in Derbyshire. This supply, however, yielded only three hundred gallons daily, and quickly gave out. Reasoning that this oil had been produced by the destructive distillation of coal at a low temperature, though ignorant of Lord Dundonald's work, he conceived the idea of producing a similar result artificially. Many experiments showed the Boghead or Torbanehill gas- coal, in West Lothian, to be the most suitable for his pur- pose, and the celebrated Bathgate works were soon founded. Lamp oil was the principal product, but lubricating oils and solid paraffin were also produced. Markets were created for the products, suitable lamps introduced, and " paraffin oil," as it was called, rapidly became the source of light throughout the Kingdom. The success of the manufacture led to the erection of a number of works in Britain and on the Continent, some of the latter importing the Torbanehill coal for distillation. Factories were also started in America to treat the native coals. When petroleum began to be produced in quantity from the springs in Pennsylvania in 1859, these factories were ready to be utilised for its refinement, and led to the rapid development of the American petroleum industry, which soon became a formidable rival to the Scottish manufacture. In 1862 the supply of Torbanehill gas-coal, which had ^^.elded about one hundred and twenty gallons of crude oil to the ton, began to fail, and recourse was had to bituminous shale, which yielded from thirty to forty-five gallons only. Competition with .\merican oil then began to be seriously felt, and in 1873 oils from Russia and the East commenced to be largely imported. Ammonium sulphate, a by-product of the process, had, however, begun to be used in quantity, and was supplanting Peruvian guano as a nitrogenous manure. But in 1890 its price fell rapidly in consequence of the importation of nitrate of soda. This long series of checks necessitated constant improve- ments in processes, with the result that at the present time treatment of a shale yielding twenty gallons of oil to the ton is profitable, while the yield of ammonium sulphate has increased from sixteen to sixty pounds per ton. The survival of this important home industry has undoubtedly maintained the light of the people at about half what it would otherwise have risen to, and paraffin oil is to-day considerably cheaper in England than it is in the oil-refining districts of America. The process as now carried out comprises two main divisions. In the first, the shale is distilled in vertical retorts, into which it is delivered at the top, descending slowly, with a gradual increase of temperature as the ash is removed by mechanical means beneath. Steam is intro- duced below, as well as the permanent gas which is produced during the distillation, no other fuel being required. The products of the distillation are ammonia liquor and " crude oil," wliich collect in two layers in the receivers. In the second division the crude oil is refined by alternate dis- tillations with fractionation into the several products, and separate treatments with oil of vitriol and caustic soda. By the distillation of the crude oil " green naphtha " is first produced, followed by " green oil " as the temperature rises These are collected separately. The former is agitated with acid and alkali, and redistilled with the production of naphtha and motor spirit. The green oil is subjected to a series of such operations by which it is separated into burning or light oils, intermediate, and heavy oils. The two latter series are cooled to remove the solid paraffin, and used for gas enrichment, liquid fuel, and lubrication. Liquid fuel has a thermal value greater by fifty per cent, than that of coal, and has the further advantage for naval purposes of easy stowage and of smokelessness, which render its complete triumph certain. '''"'^"' ''''■ KNOWLEDGE. 71 /^. ^IL^^, ^EA^.^ yjUjU^CL ^.^^, ^ .^^W . SIJl. .^a^, Z^.:^. ^ ^'' Mfff^^^, SoLt/m^^L, ^h~&-/tA^ . c^^€£j?t enter into direct combination with magnesium, whereas amorphous boron yields a boride corresponding to the formula Mg;,Bj, which appears to be the only boride formed by heating the two elements to red-heat under the ordinary pressure. By heating this boride at a high tern- 82 KNOWLEDGE. March, 1915. peralure the magnesium is expelled, and a residue containing most of the borou in a crystalline state is left. CRUDE NITROGEN IN NATURAL GASES.— The crude nitrogen fractions separated from natural gases, such as fire-damp and the gases emitted by thermal springs, have been examined by MM. Moureu and Lepape {Comptes Rendus, 1914, Volume CLVIII, page 839). The analyses show that the crude nitrogen is remarkably constant in its composition, whatever its origin, and is composed of very similar proportions of nitrogen, argon, xenon, krj'pton, and heUum. From this fact the conclusion is drawn that these constituents have a common origin, possibly, in the nebulous period. Variations in their quantities may be attributed to diffusion or other physical processes. NICOTINE FROM WASTE TOBACCO LEAVES.— A description is given by MM. Chuard and Mallet (Schweiz. Apoth. Zeit., 1914, Volume LII, page 424) of the method used in Switzerland for the manufacture of nicotine from the leaves rejected as unsuitable for the preparation of tobacco. The usual process is to extract the nicotine from these leaves immediately after the removal of the crop of choice leaves, but the experiments cited show that this is a mistake. If the stripped stems be left in the ground, and the soil treated with sodium nitrate, there will be a further growi;h of leaves, and consequently an increased yield of nicotine. For example in some cases the amount of the alkaloid obtained was increased by as much as seventy- seven per cent. WTien the nicotine was extracted from the plants at once the average yield was 0-725 gramme per plant, whereas, when the leaves were allowed to grow again, the yield was increased to 1 -284 gramme. It was proved that the sodium nitrate was not directly responsible for the production of nicotine, but that it acted indirectly as a fertiliser, stimulating the growth of the plant. The proportion of nicotine showed considerable variations in different parts of the same plant, much more being present in the roots and shoots than in the stems. GEOGRAPHY. By A. Scott, M.A., B.Sc. STREAM-VALLEYS AND THEIR MEANING.— The three chief processes operative in the development of the " thalweg " of a stream are vertical down-cutting, lateral cutting, and " sweep " or the down- valley migration of the meanders. The first of these is dominant when the bed of the stream is considerably higher than the local equi- librium level, so that the stream tends to cut vertically downwards through the subjacent rocks. The result is typically a narrow gorge, with steep sides, and following the course which the stream had before the initiation of the dovm-cutting. Wlien the gradient is low, the second process is the one which is most active. The stream tends to swing from side to side in its valley, so that a differential wear on the channel ensues. As is well known, the maximum deposition occurs on the inside of the meanders, and a complementary corrosion on the outside. This seems to be mainly due to the current tending to move in a tangential direction at the bends, this tendency increasing with large volume and low gradient. The ultimate form, therefore, is a scalloped outline, wth large circular meanders sym- metrically arranged. The comparative rarity of this form is due to the operation of the third process, which, in general, is most important, and leaves the greatest ultimate impress on the shape of the valley. In addition to the tangential flow at a bend, there is a strong tendency, due to the down- stream component of gravity, for the stream to take the shortest course, ?.£•., that round the inside of the bend. The actual course of the strongest current is the resultant of these tivo, and this explains not only the asjonmetric erosion of the meanders, but also the tendency 'of the latter to migrate down-stream. Circumstances which favour this migration are, low gradient with but little down-cutting, and a large volume of water carrying coarse material. In a river with intrenched meanders the solid rocks resist all three processes, but in a broad valley with rock sides the latter oppose lateral cutting, while the soft alluvial material of the valley-flat offers little resistance to sweep. The rate of upUft is often an influential factor in determining which of these processes has had the greatest effect. If the uplift be rapid, down-cutting becomes pre- dominant, and the stream entrenches itself in its original course. If the rate of uplift be equal to, or less than, the original rate of down-cutting, lateral cutting and down- valley sweep come strongly into play, with the formation of broad, regular curves, the outsides of which are usually steep and undercut, and the insides smooth and shelving. J. L. Rich (Journal of Geology, July-August, 1914) has classified valleys into three types — Open ^'alleys, Intrenched Meander Valleys, and Ingrown Meander ^'alleys — and has considered the formation of each type in terms of these processes. The Open Valley may either be straight or meandering, with wide, open curves and steep sides. The Intrenched Meander Valley, which is apparently the same as the Incised Meander type of other authors, is " one whose stream, having inherited a meandering course from previous erosion cycles, has sunk itself into the rock with little modification of its original course." The windings of the stream follow those of the valley, and river-flats are conspicuously absent. The Ingrown Meander Valley is one which has either developed a meandering course or has expanded an inherited one. This type is characterised by steep, undercut sides on the outside of the curves, and gentle deposition slopes on the inside. The first of these types is formed when a comparatively straight stream undergoes a rapid uplift. The stream entrenches itself by down-cutting, which continues till grade is reached, when lateral cutting comes into play. This, however, is soon superseded by a down-stream migration of the bends, and the final form is either a broad, open valley, with flat bottom and long, flat curves, or a steep-walled, narrow V-shaped valley. The Intrenched Meander Valley results from the rapid uplift of a meandering stream, which continues to hold its original course, and to entrench itself deeper into the subjacent rocks as long as down-cutting is the principal factor. This tj'pe is rarely found, because, when the upUft ceases or becomes slow. Ingrown Meander Valleys develop owing to the operation of the other processes. This third tj'pe generally results from the gradual uplift of both straight and meandering streams. The meanders tend to increase through lateral cutting, with the consequent corrosion on the concave sides and deposition on the convex, while sweep leads to asymmetry of the bends, and finally to their down-stream migration. This is particularly the case when uplift ceases and a flood-plain forms. Obviously the whole three types may be present in a single drainage system, which, for example, undergoes a rapid uphft. The main stream would form an Open Valley where originally straight, and a valley of the second type where originally meandering, while the tributaries of the upper parts would develop Ingrown IMeander Valleys, as their rate of uplift would be relatively slow. GEOLOGY. By G. W. Tyrrell, A.R.C.Sc, F.G.S. RAISED BEACH FEATURES IN ARR.\N.— The two figures give illustrations of sea-wear during the period of the ten-foot raised beach which fringes the island of Arran. In Figure 69, on page 80, a rock-arch is shown, which has been eroded in the soft Triassic sandstones and grits at Largybeg Point. The view was taken from the sea. The arch occurs just above high-water mark at the extreme seaward edge of the raised beach. It was initiated by the erosion of a soft band, the weathering of which had caused the deep March, 1915. KNOWLEDGE. 83 nick in the sky-line seen towards the right side of the photo- graph. The collapse of the block of sandstone which for- merly filled the arch took place along well-marked joint- planes, seen on the right side of the arch. Figure 70, on page 80, shows caves formerly eroded by the sea on the ten-foot raised beach platform of the Holy Isle, opposite Lamlash. These are well above high- water mark, and make a recess in the cliff which rises at the back of the raised beach. In both photographs the sandstones show a remarkable hollow weathering, frequently with raised ribs, forming a reticulated pattern. This is supposed to be due to variations in the quantity or composition of the abundant calcareous cement of the Triassic sandstone. The weathering picks out with great delicacy those parts which are more sus- ceptible to solution and decay. WATER SUPPLY IN MILITARY AREAS.— The Geological Survey has just issued an interesting pamphlet entitled " Notes on Sources of Temporary Water Supply in the South of England and Neighbouring Parts of the Continent." This was written primarily to aid the Royal Army Medical Corps of the First London Division Territorial Force in finding drinking water at short notice by temporary works. It is pointed out that all running streams are highly dangerous as drinking water in a seat of war or populated area, and wells, although not subject to the same sweeping condemnation, are liable to suspicion, especially when shallow. All water obtained from superficial deposits is liable to contamination in these areas, and requires careful testing before use. In choosing a site for a well, a warning is given to avoid the neighbourhood of obvious sources of pollution, such as farmyards, cemeteries, sewage works, etc., and to make a trial farther up a valley than any of these dangerous sites. On chalk areas running water is usually sparse, and the water is trapped within the fissures of the rock. This supply may be discharged by springs at the outcrop of a relati^'ely impermeable stratum, or may be reached by wells sunk below the plane of saturation. The chalk supplies hard but usually pure water. These considerations apply to a large part of the war area in Central and Northern France and Belgium, where the strata are generally similar in age and composition to those of the London and Hampshire basins, but the tract of ground east of Valenciennes presents quite different problems. It consists of highly inclined or vertical strata of Devonian and Silurian ages, forming the hills of the Ardennes. In tliis area recourse will doubtless be had to springs, many of which are to be trusted. No water, however, from what- ever source, should be used without testing. METEOROLOGY. By William Marriott, F.R.Met.Soc. THE WEATHER OF MARCH.— The general meteoro- logical features of the month of March are very irregular, but its main character is that of boisterousness and cold. Sometimes a strong north-east wind is prevalent, which, when it lasts many days, induces a rapid evaporation from the soil, respecting which there are numerous old proverbs, such as : — " A peck of March dust is worth a king's ransom." " A dry and cold March never begs its bread." March was a very cold month in the years 1845. 1865, 1883, and 1892 ; and it was a ver>' mild month in the years 1841, 1859, 1882, 1893, 1896, 1903, and 1912. The average mean temperature at Greenwich for March is 41°-9 ; in 1859 it was as high as 46°-8, while in 1845 it was as low as 35° -6. The average maximum temperature is 49° -8 ; the highest mean was 56° -9 in 1893 and the lowest 42° -7 in 1845. The average minimum temperature is 35° -1 ; the highest mean was 40° -5 in 1859, and the lowest 29° -3 in 1883. The absolute highest temperature recorded was 71°-5 in 1848 on the 31st, and the absolute lowest 13°-1 in 1845 on the 14th, and also in 1890 on the 4th. The average number of days on which the temperature falls to or below the freezing-point is ten. In 1845 there were four days on which the temperature was continuously below the freezing-point. The average rainfall for the month of March is 1-52 inches; the greatest amount was 4-05 inches in 1851, and the least 0-17 inch in 1852. The heaviest fall in one day was 1-21 inches in 1832, on the 14th. The average number of " rain days " {i.e., on which 0-01 inch fell) is 13-2, the greatest number of days was twenty-two in 1848 and 1896,' and the least three in 1852. Snow falls on the average on three days. Hail or " graupel " {i.e., soft hail) usually falls on one or two days. The average amount of bright sunshine at the Kew Observatory, Richmond, is one hundred and six hours. The average barometric pressure in London for March is 29-955 inches, the highest mean was 30-374 inches in 1854, and the lowest mean was 29-531 inches in 1909. " March many weathers." " March comes in like a Uon and goes out Uke a lamb." WEATHER FORECASTS BY CINEMATOGRAPH.— In an interesting article on " Forecast Distribution," by Mr. G. W. Smith, in the Monthly Weather Review, it is stated that the display of weather forecasts on moving- picture (cinematograph) screens is the latest method em- ployed in the United States for giving the information to the pubhc, and was successfully begun in March, 1912. This means of forecast display is now used in eight cities. Mr. Smith also says that the Weather Bureau has ever been alert to take advantage of every opportunity tending to the betterment of the forecast distribution, and is to-day making the forecasts available to more than five and a half million persons (mostly by telephone), exclusive of those supplied through the daily newspapers, daily weather maps, display of flags, and on moving-picture screens. MICROSCOPY. By J. E. Barnard, F.R.M.S. MICRO-ORGANISMS AND THE WAR— In all wars of any magnitude, other than the one now in progress, the loss of life from disease has been considerably greater than that resulting from wounds. In the present war the bacterial foes are being so efficiently dealt with that the state of affairs is likely to be reversed, thanks to the efficiency of the Army Medical Service and the great efforts that are being made to lessen both medical and surgical infection. There are many causes operating to produce this result. Of course, general hygiene has been very carefully attended to, so that the sanitary conditions in camps and other places where men are gathered together for training are very much better than have ever been obtained before. At the same time, the method of vaccination, particularly against typhoid and tetanus, has been exceedingly efficient. In the case of typhoid, which has been the most prevalent of all epidemic diseases in previous campaigns, the result has been nothing less than extraordinary, and the method of anti-typhoid inoculation has proved a marvellous success. No method in preventive medicine can be infallible, but this one has approached as nearly to that state of affairs as can be hoped for. It is very much to be regretted that some people in this country — well-intentioned, it may be, but sadly lacking in scientific insight — have tried to per- suade men against being inoculated for typhoid. The results are not only likely to be injurious to those who refuse to submit to what is, after all, but a trivial infliction, but constitute, at the same time, a serious danger to their fellow-men. The Army Council has been well advised, no doubt, in not taking any drastic steps to put an end to the anti-vaccination propaganda. At the same time, there is not the slightest doubt that in cases where the anti- vaccinationists have been successful in fomenting a feeling of resistance, fortunately not very many, the results have 84 KNOWLEDGE. March, 1915. been unfortunate enough for the victims in\-olved. Pre- ventive medicine has now become the most important branch of medical research, and the results which have been obtained more than justify any methods that have been decided upon at the present juncture. The danger from epidemic diseases may, and probably will, become more pronounced as the summer approaches ; but there is this to be said : the longer it is deferred, the more efficient become the means to combat the danger when it arrives. One important factor — the water supply — has been dealt with very thoroughly, and it is not too much to say that at the present time arrangements are in force which, if only carried out thoroughly, as they should be, leave little room for any danger occurring either to the men under training, or to those actually on service at the front. As to the danger of wound infection, that is a very real one. Those fighting in France are under the influence of a soil that is highly manured, and which is as a result highly productive. Its verjf productivity shows that it is a good bacterial culture medium, and the result is that a wound, when it occurs, is at once exposed to a chance of bacterial infection against which it is extremely difficult to provide, although the men are supplied with first-aid appliances of the best description. As a result, it is a point for discussion whether an aseptic or antiseptic method of dealing with wounds is, under such conditions, the more efficient. There is much reason to expect that the methods of Lister and antiseptic methods in general will have to be reintroduced, and that these may prove, after all, to be the soundest and most practical when dealing with infected wounds. Bacteriological investigations are now in full working order at the front, and field laboratories are provided, well equipped in every respect for efficiently carrying out their diagnostic work. There are a large number of organisms that have to be provided against, and some few of these are illustrated here. Microscopists have not of necessity a collection of bacterial preparations at their disposal, and it is for this reason that the photo-micrographs accompany- ing this article have been reproduced. They by no means represent all the organisms that will be met with, but they are at least a fairly representative series. Description of Figure 71. a — Staphylococcus pyogenes aureus. x 1500. A spherical organism, about 0-75(ii in diameter, which stains easily with all aniline dyes. It is the commonest of all organisms met with in suppurative conditions, such as abscesses and boils, and is present normally on the skin, in the mouth, and even in the air. b — Streptococcus pyogenes. x 1500. Occurs in chains, each individual organism being from 0-75 to l;x in diameter. It stains well w-ith all aniline dyes. Fission takes place in one direction only ; hence the chain formation. The chains vary in length, and may be modified by cultivation. It occurs in inflamed conditions, in gangrene, and in acute abscesses, and is also the cause of erysipelas. There are several varieties of the organisms, but they are verj' closely allied. c — Streptococci in pus. x 1000. d — Streptococci in milk, x 750. e — Bacillus tuberculosis in giant cell. x 750. .\ slender rod with rounded ends, which has a beaded appearance when suitably stained. It does not stain well with aqueous solutions of dyes. Its growth in artificial cultivation is very slow, several weeks being required at 37° C. Man is attacked at all age-periods with tuberculosis, its manifestations differing somewhat at varying stages of development. It is not an immediate accompaniment of the early stages of war, but is only too likely to occur at a later stage in those who have become enfeebled by exposure or un- avoidable privation. / — Tube cultivation of Bacillus tuberculosis. Natural size. Three months' growth. g — Phagocytosis. x 750. The leucocytes in the blood stream ingest any bacteria present, and so rid the body of the infection. Ii — Micrococcus Meningitidis. x 1000. Occurs as single 'cocci or as diplococci within the leucocytes. It stains well with ordinary dves, and grows freely at 37° C. on suitable culture media. It is the specific cause of epidemic cerebro-spinal menin- gitis, commonly known as " spotted fever." Description of Figure 72. i — Bacillus tuberculosis in sputum, x 1500. y — Diplococcus pneumoniae. Pure cultivation. X 1500. It retains its vitality on ordinary culture media for but a short period. It stains readily with ordinary aniline dyes and by Grams method. /t — Bacillus tetani. x 1500. A straight rod with rounded ends, which forms spores freely. The spores are frequently present in the dejecta of cattle and horses, and in the earth, so that wound- infection from this source is an ever-present danger. / — Bacillus typhosus. Pure cultivation. x 1500. m — Spirillum cholerae Asiatica. Pure cultivation. X 1 500. Curved rods, 1 to 2/j. in length, sometimes forming a half-circle. Often referred to as the " comma bacillus." n — Bacillus typhosus, showing flagellae. x 1000. o — Diplococcus pneumoniae. Film preparation of blood. X 1000. p — Bacillus diphtheriac. x 1000. PHOTOGRAPHY. By Edgar Senior. MAKING NEGATIVES FROM BLACK AND WHITE ORIGINALS. — It is sometimes required to copy pen-and- ink drawings, printed matter, and so on, and to obtain negatives that will yield proofs in pure black and white, in which case the deposit on the plate, which corresponds to the high lights, must have great opacity, while the shadows or lines must be repi'esented by clear glass. To those who are accustomed to the manipulations connected with the wet collodion process the production of the requisite type of negative would not present much difficultv, since the intensification required in order to gain the necessary- opacity is both quickly and easily accomplished. In the case of gelatine dry plates, although there are a number of ways of intensifying the image taken upon them, the time occupied in the manipulations is much longer, as more thorough washing is required between each operation ; but even then the shadows, as a rule, are not represented by the clearness of collodion. There is a deposit which it is difficult to get rid of which increases as the opacity grows, especially if a full exposure has been given ; and if the exposure has been short it is difficult to intensify with any degree of satisfaction. Thus, chiefly owing to the greater sensitiveness of the gelatine plate, a sUght action takes place, and a small deposit is formed over those portions of the film which should be perfectly transparent. One of two things, therefore, remains to be done : either to make the best we can of the conditions as they stand, or to use such means as will modify the results it is desired to obtain. Adopting the latter course, the first thing that should be done is to employ a process plate and give a full exposure, but without in any degree over-exposing, and use a strong source of light whenever possible for the illumination of the original. For development the ordinary pyro-soda developer with an extra quantity of bromide has been found to answer well in prac- tice. The development of the image, however, niust be \'ery carefully watched, and at the first appearance of any cloudine--s the negati\'e must at once be placed (without washing) into a dish containing a solution of citrate of soda, of a strength of about fifteen grains to the ounce of water; •March, 1915. KNOWLEDGE. 85 Figure 71. Bacteria which have to be combated during the wm,-. For descriptions see page 84. 86 KNOWLEDGE. March, 1915. ^ ^ \ r «^.Vi. 4^ ^;- '^'-<. -'* /».,'- ^^ /^J ^ S <^~ l>.^ '"*iVT<- V » *■ ■ m M- ir- »» i> ■' '.*; ^ "'-iitj-l^ • f^' ■ -^^.. n Figure 72. Bacteria which have to be combated during the war. For descriptions see page 84. March. 1915. KNOWLEDGE. 87 or, if the plate be known to be over-exposed, a little of this solution added to the developer previous to the commence- ment of development will in most cases work wonders. The plate should always be allowed to remain in the citrate of soda solution for about half a minute, when it is taken out and replaced without washing in the developer again, and development allowed to proceed until the requisite density is obtained. If, after fixing, the lines or shadows of the negative appear to be at all clogged, the image, after very thorough washing, should be treated with Farmer's reducer, prepared as follows : — A. Potassium ferricyanide ... ... 24 grains Water ... ... ... ... 1 ounce B. Sodium thiosulphate (" hypo ") ... 96 grains Water ... ... ... ... 1 ounce The solutions A and B must be mixed together at the moment required for use, as thev do not keep when once added together. If treatment with this reducer diminishes the density of the high lights, then intensification must be resorted to. For this purpose Monchoven's intensifier will be found very suitable, as it gives great density, and is, at the same time, non-staining ; and, moreover, intensification can be repeated if necessary'. The following is the formulae for the solutions : — No. 1. Mercuric chloride ... ... ... J ounce Potassium bromide ... ... J Water ... ... ... ... 20 ounces No. Silver nitrate Water (distilled) i ounce 10 ounces No. 3. Potassium cyanide (pure)... ... h ounce Water (distilled) ... ... ... 10 ounces No. 3 is added gradually to No. 2, when a dense precipitate at once forms ; as more of No. 3 is added the precipitate first formed begins to dissolve up, and when only a small quantity remains the solution is ready for use. There must not be any excess of potassium cyanide. This solution is kept in a stoppered bottle, labelled " Silver Cyanide Solution." The negative to be intensified is placed in No. 1 until thoroughly bleached ; it is then very thoroughly washed, and then placed in the silver cyanide solution to blacken. The necessity of thorough washing after every operation, and especially after treatment with either " hypo " or mercur\', cannot be too strongly impressed, nothing less than from a quarter to half an hour under a constant stream of water being sufficient. In fact, if it is a subject of importance that we are at work upon, an hour is sometimes occupied in washing ; and in this way we never fail to obtain clean and brilliant negatives suitable for any purpose that may be required of them : certainly in any class of negative work where these agents are employed, the secret of success lies in the thoroughness with which the washing is performed, and when these conditions are fulfilled a negative intensified with mercury is both bright and clean, and of considerable permanence. But the fact remains that for this particular class of work the results are not equal to those obtained upon wet collodion. PHYSICS. By J. H. Vincent, M.A.. D.Sc, A.R.C.Sc. SELENIUM CELLS. — The term " selenium cells " may be suitably confined to photo-electric cells in which one of the electrodes consists of a layer of selenium. Cells of this type were investigated by Minchin. A strip of aluminium is coated with selenium, raised to a temperature of 200° C, and, after being kept at this temperature for some hours, is slowly cooled. The prepared strip is now dipped into the cell, which contains acetone, the other electrode being a platinum wire. If the two electrodes are now connected to an electrometer, this instrument indicates a difference of potential between the electrodes when the selenium surface is illuminated. The selenium becomes positively charged with respect to the acetone. The difference of potential varies as the square root of the intensity of illumination. Photo-electric cells of this character are extraordinarily sensitive : by their means Minchin was able to detect the effect of the light from planets and stars. SELENIUM BRIDGES.— An apparatus in which the change in the electric resistance of selenium when illumin- ated is studied may conveniently be termed a " selenium bridge " to distinguish it from photo-electric cells with a selenium electrode. Selenium is a verj' poor conductor of electricity, but becomes more conductive when heated for some time at 200° C, and then slowly cooled. In this condition its electric resistance decreases under the influence of Ught. The effect of light is practically instantaneous, but the recovery on its withdrawal is gradual. In order to render the fall of the resistance of selenium on illumin- ation easily demonstrable, it should be arranged that the initial resistance of the bridge is so low as to allow of its easy measurement. This is readily managed b}' coating a cylinder of mica with selenium, and winding a pair of copper wires on it in a double spiral, so that the wires are insulated from each other by the selenium. The resistance between the wires should now be measured, and, if all is right, this should be several megohms. The whole is now heated and annealed, when the resistance in the dark \vill be found to have fallen to a value easily measured. On exposing such a bridge to bright sunlight, its resistance may fall as much as fifty per cent. Bridges made on this plan, and convenientlv mounted for experimentation, can be procured from instrument-makers, who catalogue them as " selenium cells." SELENIUM CRYST.\LS. — Most experimenters who have worked at the curious photo-electric properties of selenium have used the material in the state into which it is brought bv slow annealing. The mass is then probably a congeries of interlacing crystals. Recently single crystals of selenium have been studied by Brown and Sieg {Physical Review, ,\ugust, 1914 ; Philosophical Magazitte, October, 1914). By emplojang a needle-shaped crj'stal, it was first shown that, when silver electrodes pressing on the crystal were used, the resistance of the whole lay chiefly in the ci-ystal, and not at the contacts. Next, it was proved that, when the resistance decreases on illumination, the decrease is due to a change of resistance in the crystal itself, and is not limited to the contacts. So long as any light fell on any part of the crvstal there was a marked fall of resistance, even though the illuminated portion of the crystal was not in the direct line of flow of the current. This transmission of the effect of light to a distance was well shown in a remark- able experiment. A long, thin crystal was held between electrodes at one end, and a narrow beam of light was allowed to play on the crystal at various points in its length, while the resistance across the end between the electrodes was measured. It was found that the fall in resistance was as great when the light struck the crystal at the end remote from the electrodes as when it fell close to them. We thus have the amazing result that the action of the light may be transmitted laterally to a greater dis- tance than ten millimetres. The authors are incUned to the view that, when light acts on a crystal, it operates some mechanism which controls by secondary action the conductivity of the whole crystal. SALTS COLOURED BY KATHODE RAYS.— An interesting paper on this subject was read before the Physics Section of the British Association at the .Australian meeting by Professor E. Goldstein, who discovered the effect, and has done most of the work on the subject. The paper is reported in Nature of December 31st, 1914. If kathode rays fall on certain salts, such as common salt, 88 KNOWLEDGE. March, 1915. potassium chloride, or potassium bromide, vivid colours are immediately produced. Common salt becomes yellow- brown ; potassium chloride turns a beautiful violet ; potassium bromide becomes a deep blue colour ; sodium fluoride takes on a fine rosy tint. The colours so acquired are permanent, if the specimens are kept in the dark at ordinary laboratory temperature ; but in the daylight, and also under heat, the colours gradually disappear until the original white condition is again reached. SoUd solutions, produced by fusing a small quantity of a colourable salt with a great mass of a salt which itself remains colourless in the kathode rays, acquire brilliant colours when subjected to the rays, the colour assumed depending on the solvent as well as on the solvend. Very small admixtures are sufficient to produce intense colours. The first theory proposed to account for these effects was that of Wiedemann and Schmidt, who regarded the phenomenon as consisting in chemical reduction. Thus, in the case of potassium chloride, the chlorine would be set free, while the remaining potassium is dissolved in the unaltered salt, which it colours. In support of this theory Giesel coloured rock-salt by heating it in the vapour of sodium or potassium. But the Giesel salts, although they look like those coloured by the kathode rays, have quite different properties in other respects. They do not fade on exposure to light ; they give alkaline solutions, while the kathode ray-coloured salts give neutral solutions ; the Giesel salts do not give marked photo-electric effects, as do the Goldstein salts. Finally, they are not phosphorescent, while the Goldstein salts are. Goldstein has made salts acquire all the properties of the Giesel salts by the pro- longed action of kathode rays, the temperature of the salts being allowed to rise during the bombardment. To these salts, and to tho.se produced by Giesel, the theory of Wiede- mann and Schmidt probably applies, while the explanation of the Goldstein effects is that separation of the constituents of the molecule occurs, but that neither constituent is removed complete!}'. On this view the components remain at quite small distances apart, and are thus ready to re-combine. RADIO-ACTIVITY. By Alexander Fleck, B.Sc. DEFLECTION OF RECOIL PARTICLES.— It was mentioned recently in these notes that, when an a-particle carrying a positive charge was liberated, the residual part of the atom also acquired positive electricity. Just as a gun starts travelling with a certain relatively small velocity in the direction opposite to that of the discharged bullet, so when an a-particle is sent off with a large initial velocity the large part of the atom remaining recoils with a velocity which, although small, is appreciable, and, as stated above, with a positive charge. In the Februan,' number of The Philosophical Magazine, \A'almsley and Jlakower describe the behaviour of this recoil particle from radium-A when it is subjected to a strong magnetic field. In such a field ^-rays are completely deflected, and no trace of them is found beyond the borders of the field, while the 7-rays are not known to be influenced at all ; a-rays are deflected slightly, and travel along the circumference of a circle of large radius. It is found that the recoil particles also travel along the circumference of a circle, of which the radius is double that of the circle belonging to the expelled o-particles deflected by the same field. GYROSCOPIC ATOMIC MODEL.— In the same journal Dr. A. C. Crehore contributes a paper giving his views on atomic structure. One great point of difference between his model and the more generally accepted Rutherford model is that, whereas the latter supposes that the positive charge is concentrated on a very small nucleus in the centre of the atom, this gyroscopic model suggests for the distribution of the positive electricity a sphere of which the diameter is of the order of 10-'" centimetres, and within which the elec- trons vibrate, their " enormous frequency of orbit revo- lution " confining them to one plane. It is not possible to discuss fully this theory here, but one point may be raised. Dr. Crehore deduces from his hypothesis that " beta-particles may come from any electron in the atom. ... In the central nucleus theon,' they cannot come from the outside rings, and must be restricted to the inner electrons or the nucleus itself." It has been proved, however (Journal of the Chemical Society, 1914, Volume CV, page 247), that the /3- particles are entirely different from the majority of the electrons which are present in the atom, and the number of which can, in many cases, be altered by chemical means. In this respect at least, therefore, the gyroscopic model is not so satisfactory as the theory which supposes the atom to consist of a nucleus surrounded bv a ring, or by rings, of electrons. ZOOLOGY. By Professor J. Arthur Thomson, M.A., LL.D. GIGANTIC CUTTLEFISH. — C. Ishikawa and Y. Wakiya describe the partly digested remains of a gigantic Squid from the stomach of a Sperm Whale. The mantle alone seems to have been about four feet in length. It is probably Moroteuthis robusta, which has been captured only twice before — by Dall and by D'Arcy Thompson. MYRMECOPHILOUS ORGANS IN A CATERPILLAR. — In the caterpillar of Lycaena orion there are two kinds of structures adapted for the attraction of ants. They have been carefully described by Ehrhardt. When the cater- pillar is touched by an ant it protrudes two papillae with glandular hairs on its eleventh segment, and a scent is exhaled which the ants like. If the ants touch with their antennae a glandular area on the tenth segment, a minute drop of secretion is exuded from a pair of slits, and this is eagerly licked off. The secretory structures are transformed glandular hairs, and they can be brought into activity by titillation or otherwise. Ehrhardt induced by electrical stimulation ten secretions in a minute and a half. The caterpillars always have ants about them, and these are doubtless of protective value. THE EXTRAORDINARY CASE OF PLATA —In 1896 Professor J. W. Gregory described and figured a Homo- pterous insect, known as " Plata," or " Phromnia," many specimens of which had formed on the upper part of a stem an extraordinary cluster, like a flowering spike. The species occurs in two forms, green and reddish, and Pro- fessor Gregory's figure showed the green individuals on the upper part of the stem, and the red ones beneath them, the appearance being curiously like a red-flowered spike, \vith green unopened buds above. In 1902 Mr. S. L. Hinde pointed out that, although he had often seen Flata and its larva in British East Africa, he had never seen the grouping described by Gregory. He noted, however, that the red and green insects in a mixed group were very like the flowers and buds of a leguminous plant. Professor Poulton suggested that the first specimens of a group to emerge may be red, and those that issue later, green, and that Pro- fessor Gregory may have seen undisturbed groups, and Mr. Hinde groups which had broken up and reassembled. Each of the descriptions has been subsequently confirmed from tropical Africa. Dr. A. D. Imms, Reader in Entomology in the University of Manchester, relates the lii story of the observation, and adds his own very interesting experience. While touring in the Himalayan foot-hills, he came across examples of an Indian species, Phromnia marginella. The clusters of larvae looked like groups of small white blossoms. They were covered with long white waxy filaments, probably distasteful to birds. The adults were found in two colours — pea-green and pinkish buff — but they occurred intermixed. Out of seven colonies observed, all were disposed along the middle or base of branches among the fohage, and not at the apices of twigs, but they were like opening buds. The white filaments March, 1915. KNOWLEDGE. 89 of the larvae are cIo?iely allied to Chinese white wax. In addition to wax, the larvae of Phromnia marginella excrete a sweet liquid, which hardens on the leaves. According to Cotes, the natives (in Garawal) eat this stuff, and call the insects " Dhaberi," which means sheep, the reference being to their habit of clustering together, and jumping away when disturbed. Dr. Imms gives a striking photo- graph of the larvae covered with the white waxy filament. HABITATS OF NEJIATODE WORMS.— In a memoir on freshwater Nematodes in North America Mr. N. A. Cobb calls attention to the astounding variety in the habitats of these threadworms. They occur in arid deserts, at great depths, in hot springs, amidst polar ice, in the soil, in fresh water, and in the sea. " As parasites of fishes, they traverse the seas ; as parasites of birds they float across continents and over high mountain ranges." They or their ova are carried by wind and running water, by birds and insects, or by almost anything that moves. One species is almost restricted to the vermifonn appendix of man ; another has its adult form only in grains of wheat ; a tfiird has never been found, except in the felt mats on which mugs of beer are set. ' ' The sour sap issuing from the wounds of a tree, often many feet above the ground, not infrequently contains Nematodes that are specific to the wounds of that particular kind of tree." Attention is also directed to some other points of much interest. Thus eggs and larvae can survive prolonged drought, and Mr. Cobb states that the revival of mummified Nematodes may take place after as long a period as a quarter of a century. Many are parasitic and harmful ; manv that devour rotting material may help to clean things up ; and a few are known to be actively advantageous, by feeding on their injurious relatives and on baneful micro-organisms. Mr. Cobb refers also to their prolific multiplication — a single female sometimes producing thousands of eggs and to the huge numbers that may be found close together. " A thimbleful of mud from the bottom of the ocean may contain hundreds of specimens. The number of Nematodes in the top six inches of an acre of ordinan*- arable soil amounts to thousands of millions. Statistical calculations relative to the number of Nematodes in a single acre of soil near San Antonio, Texas, U.S.A., disclosed that if they could start in a procession for Washington, D.C., two thousand miles awaj', each close on the tail of the one in front, the head of the procession would reach Washington before the rear had left San Antonio." We have not verified this. SOLAR DISTURBANCES DURING JANUARY, 1915. By FRANK C. DENNETT. January proved to be a very unsatisfactory month for the solar observer o^\^ng to the prevalence of cloud. No observations were made by anv of the obser\'ers on eight days (1st, 10th, 14th, 19th, 25th, 27th, 28th, and 30th). On the 26th only taeniae were seen, but the disc never appeared free from disturbance. The longitude of the central meridian at noon on January 1st v.-as 91° 4'. No. 48 of the December list remained on the disc until January 2nd, and therefore reappears on the present chart. No. 1. — This was first seen as a group of at least a dozen spotlets and pores within the north-eastern limb on January 2nd, and followed by a faculic ridge. By the 6th there was a great leader with one larger and some small umbrae twenty-nine thousand miles in greatest diameter, and a trailer with Irwo umbrae fifteen thousand miles in diameter. On the 8th the leader was enlarged by penumbral extensions to thirty-two thousand miles. Both spots had undergone considerable change by the 9th, and the large spot was last seen close to the north-western limb on the 12th. The disturbance was eighty-six thousand miles in length. No. 2.^Two pores were seen nearing the north-western limb on the 4th, one remaining visible until the next day. No. 3. — A little group of three pores ; the larger leading was seen on the 12th and 13th. It was not observed on the 15th, probably owing to the constant passage of thin cloud making observation difficult. On the 16th the area was very facuhc, and contained several pores, closing up to the south-western limb. No. 4. — A solitary spot, about 1° in diameter, was observed from the 12th until the 23rd, On the 18th there were two minute pores away to the south-west. No. 5. — On the 16th, when first seen, there was a group of four pores ; but when last seen, on the next day, only the trailer remained. No. 6. — A small spot was observed from the 16th until the 21st, containing two umbrae and once accompanied by a pore. No. 7. — A spot with two conspicuous umbrae, some t\velve thousand miles across, was seen from the 16th until the 24th, No. 8. — A pair of pores in a facuhc ridge near the north- western limb was seen only on the 29th. No. 9. — A small spotlet with two pores on the south-west was seen only on the 29th. No. 10. — A considerable spot round the south-eastern limb was observed on January 31st, which broke into a group, undergoing considerable metamorphosis, and was last seen on February 6th. Faculae were observed near the north-western limb on the 17th, 18th (311°, 26° N. ; and 298°, 19° N.), 24th, 26th (185°, 13° N. ; 179°, 16° N. ; and 188°, 21° N.), 29th (130°, 24° N.), and 31st. North-east on 2nd (following No. 1), 22nd, 23rd, and 29th (close to the place of No. 1) ; south-west on the 5th, 9th (60°, 25° S. ; 47°, 13°, and 17° S.). The chart is constructed from the combined observations of Messrs J. McHarg, W. J. Waters, and the writer. DAY OF JANUARY, 1915. 1 r^ !\ ^ y I, 2Z 2t 2S f* a H 20 19 B f o* S' if n 9 t I f , |r» N 0 ti ;o 10 40 ui (1 10 90 « m IK m IH M eo iM m 180 191 ;« 2'' 5 53'i N.22-6 22-6 22-6 22-6 22-6 N.22-7 Neptune. R.A. Dec. h. m 738-7 758-6 758-6 7 53-7 758-8 N.20-3 30-3 20-3 20-3 20-3 7 59-0 N.20-3 Table 15. Date. Greenwich Noon. Greenwich Midnight. Sun. PEL Moon. P Jupiter. P B L, L^ T, T, Apr. 1 0 00 - 26-3 -6-5 345-5 26-4 6-3 279-5 26-4 5-9 213-5 26-1 5-5 147-5 25-7 51 81-3 - 25-1 -4-6 15-4 0 -f t9'4 - 6-6 -21-9 -14-9 + 8-6 +22-2 Apr. 3 00 6 0 ii- ^- h> ni. -248 +1-2 32*9 24*6 II 6 f II 19* 250 i'3 57'o 355*3 10 26 f 2 12 * 25'i i'4 8i'i 326'o 9 47 <■ 3 Of -25-2 +1-5 105-3 396'8 9 7^ 348' 6 ,, 16 ,, 21 ,, 24 .. . P is the position angle of the North end of the body's axis measured eastward from the North point of the disc. B, L are the helio-(planeto-)graphical latitude and longitude of the centre of the disc. In the case of Jupiter System I refers to the rapidly rotating equatorial zone, System II to the tem- perate zones which rotate more slowly. To find intermediate passages of the zero meridian of either system across the centre of the disc, apply to Ti Ta muhiples of 9" 50"° -6, 9" 55"- 8 respectively. For the future the data for the Moon and Planets in the Second Table will be given for Greenwich Midnight, i.e., the Midnight at the end of the given day. The letters in, c stand for morning, evening, taken as beginning at midnight. The dav is The Su.\ is moving Northwards at a slackening pace. Its semi-diameter diminishes from 16' 2" to 15' 54". Sunrise changes from 5" 42" to 4" 36" ; sunset from 6" 28" to 7" 18". Mercury is a morning star till May 1, when it is in superior conjunction with the Sun. Semi-diameter diminishes from 3" to 2i". Illumination increases from | to Full. Venus is a morning star. Illumination increases from TB to T^. Semi-diameter diminishes from 8" to 7". The Moon.— Last quarter 6" 8" 12" e. New 14'' 11" 36" m. First quarter 22'* 3" 39" e. Full 29'' 2" 19" e. Perigee l** 12" e. Apogee IT' 4" e. Perigee 30'' 7" m, semi- diameter 16' 34", 14' 44", 16' 44" respectively. Maximum librations3''7°N., 8" 6°W., 17" 7''S.,24'' 8° E.,30''6°N. The letters indicate the region of the Moon's Hmb brought into view by libration. E., \V. are with reference to our sky, not as they would appear to an observer on the Moon (see Table 16). Mars is still badly placed, having been in conjunction with the Sun on Dec. 24th. Jupiter was in conjunction with the Sun on Feb. 24th, and is therefore difficult to observe this month. 9' North of Venus on 15th, 4" e. Equatorial diameter 35", Polar 33". Table 16. Occultations of Stars by the Moon visible at Greenwich. From New Mooa to Full disappearances occur at the Dark Limb, from Full to New reappearances. 90 March. 191. t. KNOWLEDGE. 91 Configurations of satellites at 4'' 30° a.m. Jupiter's Satellites. Day. West. East. Day. West. East. Apl. I 3 r\ 214 .\pl. 16 231 D 4 1 2 21 0 4 3» ,,17 2 0 ■34 .. 3 2 0 4'3 ,. 18 I 0 234 •> 4 ■4 a 23 • - >9 0 I.; .. 5 42 0 13 ,, 20 21 J 3 ., 6 4231 0 ., 21 34 0 i .. 7 43 0 2 ., 22 43 G 2 >• ., S 43 0 12 ■ • 23 4i lO - 9 4213 0 .. 24 42 0 '3 ,, 10 42 0 13 ■- 2.S 41 0 23 ,, ■ I 41 u -3 .. 26 42 0 13 ,. 12 2 (--^ 413 ., 27 421 0 3 .. '3 213 u 4 .. 28 3 0 21 4« „ 14 3 u 124 .. 29 31 J 42 ' .. '5 3 u 24 ■• .. 30 32 0 4 The following satellite phenomena are visible at Greenwich, all in the morning hours: — T^ 5*" 9" I. Sh. E. ; 10<" 4" 44"" 46' II. Ec. D. ; 14" 4'' 44" I. Sh. I. ; IS"" 5" 1"" I. Oc. R.; ig'' 4'' 21°" II. Sh. E. ; 20" 4" 32°" IV. Tr. I.; 22" 3" 48°" 52' I. Ec. D. ; 23" 4" 22" I. Tr. E. ; 26" 4" 3" II. Sh. I.; 27" 3" 59" III. Sh. I.; 28" 3" 44" 17" IV. Ec. D., 4" 7" II. Oc. R. ; 30" 4" 3" I. Tr. I. The Northward motion of Jupiter will make this year's opposition (which occurs on September 17th) more favourable for European observers than those of the last four years, in which it has been very low down. Saturn is between Taurus and Gemini. Is now approaching conjunction with the Sun. Was in quadrature March 17th. Polar semi-diameter 8". Major axis of ring 40", minor 18". Angle P-5°-9. Eastern elongations of Tethys (every 4th given) 2" 0'' -8 c, 10" 2''-l m, 17" 3''-4 e ; of Dione (every 3rd given) 2" l*- -6 m, 10" ei-'S m, 18" Noon; of Rhea (every 2nd given) 3" 2" -0 e, 12" S^-O e. For Titan and Japetus E., W. stand for East and West elongations, 1. for Inferior (North) conjunction, S. for Superior (South) conjunction. Titan 1" 5'' -7 m W., 5" 5'' -2 m S., 9" 7'' -7 m E., 13" 7" 7 m I., 17" 5'' ■ 1 m W. ; Japetus 10" 2^ tn E. Uranus is a morning star but badly placed. Was in conjunction with Sun on February 1st. Neptune is stationary on 8th, diameter 2". Meteor Showers (from Mr. Denning's List) :— Radiant Date. Remarks. R.A. t Dec. Mar. - May . 26°3 + 62 Rather swift. Apl. 12-24 •■• 210 — 10 Slow, fireballs. „ 16-25 ... 301 -f 23 Swift, streaks. „ 18-23 ■■ 189 - 31 Slow, long. ,. 19 Mav 9 201 + S Slow. ,, 20 22 .. 271 + 33 Important shower, Lyrids. ,, 20-25 ... 218 - 31 Slow, long paths. „ 30 291 + 59 Rather slow. Apl.— Mav 193 + S« Slow, yelbw. Apl.— May ... 296 0 Swift, streaks. Double Stars and Clusters. — The tables of these, given three years ago, are again available, and readers are referred to the corresponding month of three years ago. Variable Stars. — Stars reaching their maxima in or near April, 1915, are included. The lists in recent months may also be consulted. (See Table 17.) Comets. — A new comet (1915a) was discovered by Mr. J. C. Mellish, about Feb. 10th, in R.A. 17^ N.Dec. 3°. Daily motion + 1", South 6'. Its place in April cannot yet be predicted. Medcalf's Periodic Comet has been detected by Miss Leavitt. It passed perihelion about 1914, June 5th (period 7 years 8 months), and is now extremely faint. Table 17. Long-period Variable Stars. Star. Right Ascension. Declination. Magnitudes. Period. Date of Maximum. h. m. s. » d. R Lvncis 6 54 18 +55 27 65 10 14-0 379 igiS-Apr. 9 V Cancri . .. 8 16 53 + 17 34 7- 1 to 12-8 272 ,, May 4 S llvdrae 8 49 S + 3 24 75 '0 '2-5 256 ,, May 9 R \irginis 12 34 12 4- 7 27 6-2 to n- I 145 May 5 V Ursae Min. 13 37 10 + 7 45 7-510 87 71 ,, May 18 R Can. Venat 13 45 18 +39 58 74 to 122 328 ,, Mar. 24 R Bootis 14 33 27 -1-27 6 5-9 to 12-2 223 ,, Apr. 21 Night Minima of Algol 1" , 5" 5''-0m, 8" l"'-8m, 10" 10" -ee, 13" Principal Minima of ^ Lyrae 9" l^c. 22" ll"*;. •4e, 28" 3"- 5 m. Period 2" 20'' 48" -9. Period 12" 21" 47" -5. REVIEWS. AERONAUTICS. The Aeroplane. — By C. Grahame-White and Harry Harper. 280 pages. 16 plates and other illustrations. 7-in. X 5-in. (T. C. & E. C. Jack. Price 3/6.) This book is a good popular account of present-day aerial machines. We say present-day because these inventions progress so rapidly that the date of publication is of importance, though no year appears on the title page. The work comprises a general history of the development of the flying machine from earliest times, and, after detailing the early experiments of Lilienthal, Maxim, and the brothers Wright, describes all the more recent machines. There is a short chapter, or rather portion of a chapter, dealing with balloons and airships, and there are incidental brief 92 KNOWLEDGE. March, 1915- explanations of such accessories as the petrol engine. Some sixteen fine plates from photographs illustrate the principal events, but it seems a pity that these have not been inserted opposite the matter to which they refer. Numerous other rather crude line drawings help to elucidate the subject. The book is clearly written in unpretentious style, and does not attempt to go at all deeply into techni- calities. A good index would have added to its value. B. B. P. ASTRONOMY. Stellar Movements and the Structure of the Universe.- — ^By A. S. Eddington. 262 pages. 4 plates. 22 diagrams. 8|-in. X 5J-in. (Macmillan & Co. Price 6/- net.) The book is on a selected yet comprehensive branch of astronomy, the subject of stellar distribution being more than two hundred years old. The two hundred and sixty-two pages are divided into twelve chapters, each of intense interest : they are written in a scientific yet popular form, except Chapters VII and X, which are mathematical. In addition to these twelve chapters there are four plates of nebulae, twenty-two diagrams, and an efficient index. We would like to make one or two comments. We have an inherent impression that when a book is called a mono- graph we may expect to find the book substantially complete upon the subject, both in its historical and present-day aspects : the dissociation of one from the other prevents the author from afiordmg a more complete account to the reader. The author has to assume that the reader knows the history and the work of the pioneers in the subject, and one is apt to get a superficial view of the state of the particular branch of knowledge treated of. Our view may be too comprehensive of what a monograph may be. True, the author, in this instance, clearly states in his preface : " No attempt has been made to treat the subject historically. I have preferred to describe the results of investigations founded on the most recent data rather than early pioneer researches. . . . But it was outside my purpose to describe the steps by which knowledge has advanced ; it is the present situation that is here surveyed." If one will only read the book — and it is a book in which every line should be read carefully — with this qualification in view, he need not allow his mind to wonder on omitted historical data ; it is essentially a survey and a thoughtful assimilation of researches in this particular and absorbing branch of astronomy during the last twenty-five years. i\Iost of the chapters are crammed with selected state- ments of facts derived from the numerous recent workers in this subject, among whom the author has been one of the most earnest and prolific investigators. Numerical references and a bibliography are given at the end of each chapter. It must not for one moment be understood that this book is a mere collection of facts from others' work ; the author both advances and explains many theories throughout to account for the numerous phenomena which stellar astronomy presents. We notice that the data in Chapter I are not quite up to date, and the omission of Professor H. C. Plummer's radial-velocities investigations is conspicuous. We hope that, should another edition be required, this and other omissions will be rectified ; and we especially desire that one or even two chapters be added, for historical interest, treating of the spade-work prior to 1890. The book is well printed, but on surfaced paper. We notice two misprints of Lalande on page 19. F. A. B. CHEMISTRY. Chemical Engineering. — By J. W. Hinchley, A.R.S.M., Wh.Sc. 103 pages. 70 illustrations. 7^-in. x5-in. (J. & A. Churchill. Price 2/6 net.) The title of this book appears too comprehensive, since it deals exclusively with the manipulation and transport of solid materials, and does not claim to cover the ground where the engineer requires the assistance of the chemist. Within its limits, however, it gives much useful information as to the different types of machinery used in chemical works, and shows which are the most suitable for special kinds of work. Mechanical details are clearly described and illus- trated, and the principles underlying the action of the machines are explained at sufficient length. But it is a pity to issue a valuabl:; little book of reference without an index. C. A. M. Elements of Qualitative Chemical Analysis. — By J. Stie- Gi.iTz. 2 volumes. 312 and 153 pages. 8J-in. x5^-in. (G. Bell & Sons. Price 6/- net each volume.) The first volume deals with the general chemical and physical principles underlying chemical analysis, and more particularly with the laws of equilibrium and the modern theories of solution ; while the second volume is intended as a practical companion to the first, with which it should be used simultaneously. The method of teaching is that employed by the author in the University of Chicago, and seems to be well adapted to develop the critical faculty in students. Nothing is to be taken as proved, but every theoretical statement is to be practically tested, and sys- tematic questions are put to make clear the meaning of every operation. There is no doubt but that anyone who conscientiously works through these volumes will have a thorough grasp of the principles of analysis, or that he will have received a good preparation for quantitative work. The second volume is interleaved with blank pages upon which the student may note anything that strikes him at the time of the experiment. C. A. M. GEOLOGY. Proceedings of the Geologists' Association. Volume XXVI. Part I. — Edited by Horace Woollaston Monckton. 104 pages. 11 plates. 7 figures. 9-in. x6-in.) (Edward Stanford. Price 2/6 net.) This part is an interesting one, and contains a paper by Mr. Reginald Smith, in which some " Prehistoric Problems in Geology " are considered, with a view to concentrating the attention of the archaeologist and the geologist on points which need to be cleared up, and which at present obscure our notions of prehistoric man. Among the questions dealt with is the current view that Britain was not finally separated from the Continent before the period of La Madeleine, the last great division of the palaeolithic Cave period. An implement exhibited in illustration of the paper, found in situ in the raised beach at Brighton, was of the St. Acheul type, which shows that the beach was not older than the St. Acheul period. An illustration, reproduced by permission (see Figure 75), shows an implement which Sir J. Prcstwich found, in 1869, at Downton, in the highest terrace overlooking the lower Avon. Other matters discussed include the freshwater gravels of Bournemouth, palaeolithic gravels at Ipswich, and in Ireland and in Scotland. The remainder of the publication consists of a brief report of the Session 1913-1914. and detailed accounts of eight geological excursions. Some excellent photo - micrographs of rocks which we are privileged to reproduce (see Figures 73 and 74), obtained in Cornwall, are introduced as illustrations in the account of the visit to the St. Austell district. All the excursions are described in the thorough and valuable manner for which the Geologists' Association is justly famed. W. M. W. The Deposits of the Useful Minerals and Rocks.- — ByF. Bev- SCHLAG, J. H. L. VoGT, and P. Krusch. Volume I. Translated by S. J. Truscott. 514 pages. 291 illustra- tions. 9-in. x6-in. (Macmillan & Co. Price 18/-.) This book is the first volume of a treatise on ore deposits, which promises to be the most comprehensive one yet pub- March, 1915. KNOWLEDGE. 93 From photographs h\ H.M. Geological Survey Figure 73. Figure 74. .\ photomicrogiaph of Luxulvanite, Luxulyan. X 30. .A photomicrograph of .Aiiorlhoclase-bearing Granite, Ordinarv Light. Greadv Ouarrv. Luxulvan. X 14. X Nicols. Figure 7d. FUnt Implement found by Sir J. Prestwich at Downton, Wilts. 1869. (Natural History Museum.) (From its Proceedings, by the courtesy of the Geologists' Association.) 94 KNOWLEDGE. March, 1915. Figure 76. Uwarf Chamaeleon {Chaniaeleon puiuilus). Figure 77. Cat Snake (Tarbophis fallaxi. fFrom "Reptiles and Batrachians," by E. G. Boulenger. By the courtesy of Messrs. J. M. Dent & Sons.) March, 1915. KNOWLEDGE. 95 lished. The literature of the subject is voluminous and widely scattered ; much of it is purely descriptive, and written from an empirical standpoint. The authors of this volume have not only " digested " the literature, but have endeavoured to give an account of the general principles underlying the genesis and occurrence of ore deposits. Witli tliis end in view, the description of separate occur- rences has been inserted only as illustrative of these principles. Therein the book differs from most previous ones on the same subject, which have been more in the nature of descriptive handbooks. The introductory part is concerned mainly with the morphology and mineral content of the various types, and includes an abundance of interesting and useful data regarding the association and relative amounts of the various elements in different ore fields. It is perhaps a little unfortunate that Clarke's " Data of Geochemistry " appeared too late for the wealth of information contained therein to be utilised. The second part of the volume deals with the difficult subject of classification, and the evolution of this from the :norphological systems of von Cotta and other early writers to the present-day genetic ones, is traced. The one finally adopted by the authors, while it does not differ radically from that of Beck, is in advance of the latter in the subdivisions of the main groups. There are four main divisions : magmatic segregations, contact-deposits, cavity-fillings and metasomatic deposits, and ore-beds. These are subdivided on the basis of the mineral content. It is only natural that the last of these groups should be the least satisfactory', as it includes many deposits the genesis of wliich is still very doubtful. The remainder of the book is occupied by a systematic examin- ation of the first two groups, and of the tin, apatite, and mercury lodes in the third. It can unhesitatingly be said that the authors have succeeded in their difficult task, and it is impossible to praise too highly the skill with which they have correlated the great accumulation of evidence. Furthermore, they have been eminently successful in their presentation of the genetic principles, and have shown that this branch of geology has a considerable claim to rank as a rational science. On the whole, the translator has done his part well, particularly in the rendering of the numerous technical terms into English. In places, however, the diction is unduly obscure, owing to a great deficiency in punctuation marks. Some terms, such as " eutecticum " and " sodium- granite," scarcely conform to English usage, while the use of the name " labradorite " to designate a rock and a mineral indiscriminately is somewhat confusing. The value of the book is enhanced by a large number of excellent illustrations indicative of the geological structure of the various deposits; but the general "get-up," though otherwise good, is marred by a number of misprints. Thus, there is one in the table on page 149, another in the formula of durdenite on page 219, while both " aragonitc " and " arragonite " appear in the one paragraph. It is some- what strange to see " aluminium " characterised as a mineral, while on page 83 " atomic weight " is used instead of " specific gravity." These, however, are only minor defects in a most useful and readable book, which can be thoroughly recommended to all interested in the subject. A. S. NATURAL HISTORY. Reptiles and Batrachians. — By E. G. Boulenger, F.Z.S. 278 pages. 202 illustrations. 9 J-in. x 6 J-in. (J. M. Dent & Sons. Price 16/- net.) Mr. Boulenger has produced a very attractive and at the same time useful book : attractive because it is simply written and has a wealth of really beautiful illustrations, and useful because many of the reptiles and amphibians described are commonly kept in captivity, or could easily be so with little, if any, discomfort to themselves. Moreover, Mr. Boulenger has introduced a classification which shows the systematic position of the animals without encroaching unduly upon the space available for the consideration of life-histories and habits. Any lover of nature will enjoy reading the book, even if " cold-blooded " creatures do not specially appeal to him. In dealing with the Tudtara of New Zealand, which has be- come almost extinct on the larger islands, though it is protected on the smaller ones in the Bay of Plenty, Mr. Boulenger shows how rapid its extermination has been by pointing out that while twenty-five years ago a specimen could be purchased from almost any dealer for from twenty to thirty shillings, the price is now about fifteen pounds. The book contains some interesting notes on the Giant Tortoises ; the South Albemarle Tortoise, attains the length of five and a half feet and weighs nearly five hundredweight. The eggs are about the size of a tennis ball, and the young grow rapidly — in fact, when four years old they are nearly two feet in length. .\n adult tortoise may not increase in size for a hundred years or more, and its length of life may be judged from the fact that specimens have been kept in captivity for more than two hundred years. These notes will give some idea of how the animals are treated, and the book deals also with Crocodiles, Lizards, and Snakes, besides the Batrachians : tailless, like the frogs and toads ; tailed, like the salamanders ; and limbless, like Ichthyophis and Typhlouectes. By the courtesy of the pubUsher, we are enabled to repro- duce two of the illustrations, namely, that of the Chamaeleon and that of the Cat Snake (see Figures 76 to 77). W. M. W. PHYSICS. The Dynamics of Surfaces. — by Professor Dr. "Med. Leonor Michaelis. Translated by W. H. Perkins, M.Sc. 118 pages. 8 illustrations. 8|-in. x 5i-in. (E. & F. N. Spon. Price 4/- net.) This book is intended as an introduction to the study of biological surface phenomena, and is primarily written to enable biologists to deal with the problems of surface reactions more fundamentally than they have done hitherto. We think that it will form an excellent guide to any serious student of adsorption and allied surface effects. The references to the literature of the subject are numerous, and will greatly smooth the path of any explorer into this important region of chemical physics. Such readers will be found among biologists, but also among those who approach the subject as chemists and physicists ; while the scientific dyer will here find much that is of interest. We find the book very free from misprints ; a curious one, however, occurs on page 104, where, in a reference to a paper by Rcinold and Rucker, the first-named author is called " Reynolds." J. H. V. Smithsonian Physical Tables.— By Frederick E. Fowle. Sixth Revised Edition. 355 pages. 9-in. x6-m. (Wesley & Son. Price 8/6.) These tables form one of a series of four volumes of tables issued by the Smithsonian Institution, the others being the Meteorological, Geographical, and Mathematical Tables. In magnitude the Physical Tables are intermediate between Kaye and Laby's Physical and Chemical Constants and Landolt - Bornstein - Meyerhoffer's Physikalisch-chemische Tabellen. An introduction of thirty-five pages deals with units of measurement and conversion formulae : this is followed by tables of formulae for conversion factors and of numerical conversion factors. Tables of mathematical functions now follow, including useful lists of differentials, integrals, and series. The body of the book of Physical Tables begins at page 68 with Strength of Materials, and consists of accurate data on many subjects of importance and interest to physicists, all well arranged and clearly printed. The volume adds another debt which science owes to the Smithsonian Institution. J. H. V. 96 KNOWLEDGE. March, 1915. TRAVEL. On the Trail of the Opium Poppy. — By Sir Alexander HosiE, MA., LL.D. 2 volumes. 300 and 308 pages. 26 illustrations. 1 map. 15 illustrations. 1 map. 9i-in. X 6J-in. (George Philip & Son. Price 25/- net, two volumes.) Ten years or more ago the Government let it be known that India was prepared to forgo her opium revenue, and that it was the Chinese craving for the drug, and not England's desire to force it upon China, which was re- sponsible for the continuance of the traffic in Indian opium. A movement was set on foot in China against the cultivation of the poppy and the consumption of opium, and in 1906 a very drastic Imperial decree was made. The terms of this will be found in Appendix I of the book before us. The British Government, by request, undertook annually to diminish the export of opium from India if the Cliinese Government carried out its arrangements for diminishing the production and consumption of opium in China. In 1910 and 1911 it fell to the lot of Sir Alexander Hosie to investigate the extent of poppy cultivation in those provinces which had previously been the chief centres of opium production. The results of his mission are given in Appendi.x II, but his two volumes themselves contain the story of his travels in a little known and in part unexplored country. It may be said at once that the account is full of interesting details, from the trials of the traveller who has to weigh out silver as currency, and always gets worsted in the exchange, to the account of the flags set out in the fields to charm away injurious insects. Sir Alexander Hosie, in a previous book — " Three Years in Western Cliina " — described the coccus which e.xcretes white wax on the branches of an ash (Fraxinus chinensis). He now records that the insect is propagated on a large leaflet privet [Ligustruni lucidwn). In Yunnan, he found that there were plantations of privet entirely devoted to the purpose, and at the end of April the mother scales, containing the minute cocci, are ready for transport to the other provinces, where the ash is cultivated. The \-olumes are well illustrated and \\-ell worth reading. W. M. W. NOTICES. TROPICAL AGRICULTURE.— The Proceedings of the Third International Congress of Tropical Agriculture, which have just been published (London : John Bale, Sons & Danielsson ; 10/- net), form a substantial volume of over four hundred pages. The volume is edited by the Honorary Secretaries of the Congress, which, it will be remembered, was held last June at the Imperial Institute. THE SYDNEY TREASURES.— The family collection of Earl Sydney, Lord Chamberlain to Queen Victoria, will be sold by auction by Messrs. Knight, Frank & Rutley, early in the season, owing to the death of the Honourable Robert iVIarsham-Townshend. The dispersal of these works of art and the library will be the most important sale since the declaration of war, and will arouse interest both in England and America. LONDON COUNTY COUNCIL LECTURES.— Among the free public lectures which will be given at the Horniman Museum during JNIarch, at 3.30 on Saturday afternoons, are the following : March 13th, " Serbian History and Folk- lore," by Mr. A. R. Wright; March 20th, "The Folk- lore of Flanders," by Mr. Edward Lovett ; and March 27th, " Bruges, Past and Present," by Miss Abram. THE GEOLOGY OF HAVERFORDWEST.— -The Board of Agriculture and Fisheries desire to give notice of the publication of a Geological Memoir of the country around Haverfordwest; price 3/6. This volume, which forms Part XI of the Memoir on the South Wales Coalfield, and is explanatory of the New Series One-inch Map, Sheet 228, describes the eastern part of the Pembrokeshire Anthracite District. UNIVERSITY OF LONDON APPOINTMENTS BOARD. — We have received a copy of a pamphlet from the University of London dealing with the work of the Appointments Board. The primary aim of the Board is to benefit the graduates by assisting them to secure employ- ment, but it would be equally true to say that its object is to assist the employer who has in it — ready to hand — a selecting medium for the higher classes of employment. INSECT PESTS AT THE FRONT.— Under the title of " The iSIinor Horrors of War," Messrs. Smith, Elder & Co. are publishing a number of articles which have appeared since the beginning of the war in the British Medical Journal, by Dr. A. E. Shipley, the Master of Christ's College, Cambridge. These articles, which are fully illustrated, deal with various insect and other pests which cause disgust, discomfort, and often disease amongst our troops now fighting in all quarters of the globe. THE ROYAL INSTITUTION.— At a recent meeting of the members a letter was read, from the Honourable Sir Charles A. Parsons, saying that it gave him much pleasure to enclose a cheque for five thousand pounds in favour of the Royal Institution, which might be of some help at the present time. There is no doubt that many societies are feeling the pinch of war, and Sir Cliarles Parsons's example is one whicli, if followed, might save much anxiety on the part of officials who arc loth to see good work stopped. LIVINGSTONE COLLEGE.— We have received from the new Principal of Livingstone College, Dr. Loftus E. Wigram, a copy of the College Year Book, which shows that this institution is still carrying on its valuable work. Besides matters of special interest to students, we may mention that the Year Book contains a number of reviews of scientific books dealing with medical and hygienic literature. One letter included is from an old student who went to a station where his predecessors had all died quickly, owing, he found, to the mosquitoes. The student set to work, and found some acres of stagnant water. This he drained and turned into a good garden ground, with the result that the mos- quitoes disappeared, and the health of the district at once improved. A FOLDING TRENCH HYPERSCOPE.— We are very much pleased to call attention to the " Metron " folding trench hyperscope, manufactured by Mr. C. Baker, of 244, High Holborn, of which already a large number is being employed by the British E.xpeditionary Force. This apparatus has been designed to enable an observer occupy- ing a trench or under cover to watch the movements of the enemy without in any way exposing hhnself. Two handles are provided, one on each side of the instrument, through which stakes can be driven into the front of the trench, thus holding the hyperscope and leaving the observer's hands free to manipulate his binoculars. An important feature of this hyperscope is that it folds, and is consequently very compact for carrying. It is made in two models ; [a) of well-seasoned three-ply wood, waterproof Government-grey painted (price l\ 5s.) ; and (b) of metal similarly painted, but of lighter weight (price £1 10s.). The mirrors being set in metal cases are well protected ; should, however, a mirror be broken, a spare one can easily be fitted by the user. These hyperscopes can be made in varying lengths, but the twenty-lour-inch model is recommended for ordinary trench work: this folds to 25-in. x 7i-in. x |-in. The size of the mirrors is 6-in. x3i-in., and, being of selected patent plate, allows prism or other binoculars to be used with the instrument. March, 1915. KNOWLEDGE. THE English Mechanic WORLD OF SCIENCE Commences with Volume C I its Second Century. For fifty yeari. it ha:^ steadily ami continuously broadened the bounds of its influence, nnd yearly added to the ranks of its thousands of voluntary helpers. We ask to-day, not for conscription, hut for universal voliuitary service in the task of enlisting the young in the sen'ite of science. It is no duty of ours to discuss whether we were re; ly as a nation for the great struggle in which the British Empire is engaged : but it is no secret that, after a generation of universal elementarv education, the majority of our countrymen grow into man- hood and womanhood ill equipped for the industrial struggle with their competitors of better-trained nations, and content to seek recreation in vicarious athletics and the unedifying, but exciting, " popular " literature of the time. Of hundreds of thousands of these it is the bare truth to say the fault is not theirs, but that of their teachers. If youth were but led jud'ciously, and without pedantry, to the realisation of the pleasures of science, aptitude and inclination would attract yearly increasing thousands to the profitable utilisation thereof in manhood One proof that this is so is the eagerness with which the English Mech.\nic is read in schools where the teichers have familiarised the children with its content^. Will more teachers make The Esclish Mechanic .^nd World OF Science their school book r If so, thousands of men and women who will read its pages fifty years hence w:ll gratefully remember them. A Specimen Copy will be sent free to any address on re(|uest. ENGLISH MECHANIC, 5. EFFINGHAM HOUSE. ARUNDEL STREET, STRAND. LONDON, W.C. Royal Naval Division PUBLIC SCHOOL BATTALION. THE ADMIRALT\- have official given * peniiissioii for raising a Battalion of 1,000 men, which will be strictfv limited 'to PuIdHc School or University Men, and who will serve together as a Unit. Training is now going forward. SERVICE For the period of the WAR. Military Training. Ages 18 35. Applicants desiring to enrol should apply at once to ROYAL NAVAL DIVISION, 6, 7, 8 Old Bond Street, London, W. GOD SAVE THE KING. Lewis's Circulating ^ Medical and Scientific Library. f o\tiini; iik svil i-.i ts ■■( Astronomy, Biology, llotany, Chemistry, Klectricity.bngineerinjf.Oeography Geology. Microscopy. Mining, Philosophy, Physics, Physiology, 5ociology, Technology, Travels, Zoology, &c., in .'nKiitinn to fcverv Branch ol Medical Science. i\ew Works and Mew Editions are added to the Library immediately on publication. Subscription, Town or Country, from 21s. THE LIBRARY READING & WRITING ROOM open daily for the use oi Subscribers. L Londo London: H. K. LEWIS, 136, Gower Street, W.C. l*rospci;tus. with QuarteHy List of Additions, post fn OUR INFORMATION BUREAU will be lound to be ot great use to Foreign and Colonial reader?. Oftentimes information is desired which is unobtainable locally, and in such cases, whether the information is of a Literary, Scientific, Trade, or other character, we undertake, for a small fee, to supp'*' the infonnation desired, if at all obtainable ; and m order to introduce our Bure to the notice of the readers of Knotcledge we will, for a limited period supply such information at the rate of 6d. per enquiry. Stamps iForeign or British) will be accepted inpayment of the Enquiry Fee, and replies will be forwarded by the earliest possible mail. We also act as Buying Agents for readers n-^ident in the provinces or abroad. Full particulars sent gratis. E. GEORGE & SONS, 23 Jacob Street, London, S.E., England. To AUTHORS. EDITORS AND PUBLISHERS. . THE . Blocks of the Illustrations that have appeared in "KNOWLEDGE" 99- CAN BE PURCHASED ^^ on very moderate terms. Reprinted from " !\noit.-lcdgc," May. 1911, isxiic. A BIRD'S-EYE VIEW OF THE HISTORY OF ASTRONOMY (WITH FOLDING PLATE). By \V. ALFRED PARR. PRICE SIXPENCE. London : Knowledge Publishing Company, Limited, Avenue Chambers, Bloomsbury Square. W.C. Advertisement Rates. £ 5. d. Whole Page - - - 6 B O ] Half Page - - 3 5 u Quarter Page - - 1 15 u tM One-Eighth Page - - - U 18 b ■ ^ One-Sixteenth Page - - U ID U Per inch, Narrow Co umn - U 7 U Half „ ** - O 4 o J Discounts for Series ok Insertions and Ratics for Special Positions, when Vacant, on Ai'1>I-Ication to The advertisement Manager, KNOWLEDGE OFFICE, AVENUE CHAMBERS, BLOOMSBURY SQUARE, LONDON. W.C. KNOWLEDGE. March, 1915. CLARKSON'S SECOND HAND OPTICAL MART. TELESCOPES. .>_■.;,. \\'ray,niuunl- ed uii massive oak lath stand with stretchers, hori- zontal and vertica! movements by Hooke's joint, slow motions. large finder, 4 astro, and r day eyepieces . . £40 4-in..fii!l,Negretti & Zambraalta/-. finder, i day, :; a>tros.. in case .. .. .. ..25 j.^-in. Baker, on ahaz. stand, horizontal and vertical motions, finder, day ami 2 astros. . . .. .. ., ..171 3i.in. Dollond, on ahaz. stand, finder, d.^y and 2 astros. ,, ...121 3-in. Steward, on altaz. with equatorial (undivided circles), i day, 2 astros. . . ill 3-in. Wood, 1 astro, and 1 da\- eyt-pieces Many others. Also P^lyepit s. Diagonals, eti- MICROSCOPES. ^ 14 14 Watson " Eidinburgh Student's *' iiino.u- lar, 3 eyepieces. 2-in., i-in., 5-in., polari- scope. and case 17170 Watson " E:dinbur^h H,** - ■;. 1 T'. I I 2 (>. i, , 2 eyepiei, e^, triple S^i'D^/^ nosepiece, and Abl>e 15 15 o j^'tff- Beck Large "London," 3 eyepieces. 2,:;, i/6. and 1/14 oil immersion objectives, triple nosepiece. spiral Abbe and iris, mechanical stage, as new Baker "D.P.H." Stand, triple nosepiece. Ablie, ami cvse Watson *' Fram," eyepiece, spiral, Abbe and iris, double nosepiece. 2/3 and 1/6 LeitZ lib, eyepiece. 3 and 7 objectives. double nosepiece. spiral Abbe and iris Beck Small "London." spiral. Abbe and iris, > expense can thereby he saved. Write or call. UfANTrn Microscopes, Objectives, etc., or whole TtMlllfcU. Outfits purchased for Cash. i \CHANGES MAIjE. CLARKE & PAGE, 23, Thavies Inn, Holborn Circus, LONDON. LIVING SPECIMENS FOR THE MICROSCOPE. Voivo\ globator, JJesniids, Diatoms, Spiro§yra. Amoeba, Actinophrys, Spongilla, Vorticella, Stentor, Hydra. Cordylopohra, Stephanoceros. Melicerta. Polyzoa, and other forms of Pond Life, Is. per tube, with printed drawing, post free. Thomas Bolton. N'aturalisl. 25, Balsall Heath Road. Birminshani. MICROSCOPIC SECTIONS ROCKS & MINERALS CUT either from Stock or Clients' owrn Materials. JAMES R. GREGORY & Co., Mineralogists, Sec, 139, Fulham Road, South Kensington, S.W. Telephone: Western *2S41. Telegtams: "Meteorites, Londij'i." SECOND-HAND DEPARTMENT. Microscopes. Telescopes, Spectroscopes, Binoculars. Surveying Instruments, &c., BY THE BEST MAKERS AT MODERATE PRICES. Liits sent po-;t iree on request. Scienti/tc Instruments Bought, Exchanged ani Sold on Commission. JOHN BROWNING, 146 STRAND, and 72 New Oxford St.. LONDON. lelegrams ; '.■\UKS," LONDON. Telephone S24 GERRARD. Established Stevens' Auction Rooms, 38, KING ST., GOVENT GARDEN, LONDON, W.C. K\ery Friday at 12.30. Sale> .ire held at the Rooms of MicKOSCopEs and Slides, Tf.i.escopes, Surveying Instklments. Electrical and Scien- tific APrARATi;s, Cameras and I. esses, Lanterns AND Slides, Cfnematograihs and Films, in great variety, Lathes and Tools, Etc. floods may be sent for inclusion in early Sales. Settlements made one week after disposal. Catalogues and all Particulars Post Free. Valuations tnr Probate or Transfer, and Sates con- ducted In an> part o( the Couiitr\. ALL KINDS OF BRITISH AND FORSIGN Mineral Specimens, COMMON MINERAL ORES, and CHOICE CRYSTALLIZED SPECIMENS at ALL PRICES oa view at RICHARDS' SHOW ROOMS, 48 Sydney Street Fulham Road, South Keosingtoa. Loadoo, S.W. PRlCh LlSl'S t^RE^. F. WIGGINS & SONS, 102, 103, 104, Mmones, LONDON, E Contractors to H..M Government rOR LAMPS. STOVES. VENTILATORS, ELECTRICAL WORK AND ALL PUhPOSES. Largest Stock in the World. Tel. No. 2248 Avenue. Printer of Knowle.lae.' JOHN KING, Uxbridge, Southal). and Ealing, I s favourably ei4uippcd fur ttie PRINTING of ^ Scientitic Books, Brochures, Catalogues, &c., and will he pleased to submit estimates. .■\iiiiress all Communications to 213. IXBRIDGE ROAD. EALING. LONDON, W. "Phone. 114^ Ealins- Binding Cases for Knowledge Volume, 1914. IN BLUE CLOTH, WITH GILT DESIGN AND LETTERING. 7s. ..;:. 425 IlluStpatiOnS, iiK,i,y :.eina Ktiil f..,c I,.,..,. Bound in Blue Cloth, Gilt Design and Lettering, 15,- net. post free within the United Kingdoni. Publishing Office: AVENUE CHAMBERS, BLOOMSBURY SQUARE, LONDON, W.C. or through any Bookseller March, 1915. KNOWLEDGE. WATSON'S MICROSCOPES The best obtainable. British-made throughout. rppirjjr'J^T' . Enable the [worker to gel the best out o( his CONVENIENT '. Every necessary movement Is embodied. STABLE * With either tripod or horseshoe loot. PRACTICAL : intended »or hard work. LAST A LIFETIME. The "RESEARCH" Microscope. Specification : — Mechanical Stage — Giving move- ments 2" X 1|". Botli milled iieads on same axis. Fine Adjustment — Side limb, vertical lever type. Coarse Adjustment — Diagonal rack, long range, enables 3" objecti\>e to be focussed when on nosepiece. Compound Substage — Rack and pinion focussing with centering screws for condenser. Movements are slotted and sprung throughout, and wear can be at once compensated. Tripod foot giving stability in any position. Guaranteed for 5 years. Fop the Ainateup op Ppofessional this instrument embodies every desirable movement, and is at once the cheapest and the best obtainable. Prices: — , Research Microscope do. do. with eyepieces No. 2 and No. 4, objectives 1" and i" (1 mm. working distance for pond life or blood counts), aplanatised Abbe illuminator with iris diaphragm. In mahogany case Full details of the above, and also of 32 Different Models at all prices, will be found in Watson's Micro- scope Catalogue, No, 2k, which will be forwarded gratis on application. £12 10 0 17 17 6 APPARATUS PHOTO-MICROGRAPHY. METALLURGY. BACTERIOLOGY. FOR:— POND LIFE. PETROLOGY. PROJECTION. H.fflMATOLOGY, &c,, &c. W. WATSON & SONS, LTD., Contractors to 1b.^. governments, 313 HIGH HOLBORN, LONDON, W.C. Branches : 16 Forrest Road, Edinburgh; 196 Great Portland Stre»t, London, W. Dei6ts : 2 Easy Row, BirminfSham; 78 Swanston Street, Melbourne, Australia; 212 Notre Dame Street West, Montreal, Canada. Optical Works— HIGH BARNET, HERTS. ESTABLISHED 1837. THElONDON'MIGROSGOPE ("REGENT " Model). This instrument is somewhat .similar, though larger, than the Large "" London" Model. The slow motion is about four times as fine, working in the most per- fect manner by means of micro- meter screw and a .system of levers. The limb is provided with a handle for lifting. Still more room is allowed for the rack and pinion, centring and substage. The substage swings out laterally. An iris diaphragm is set in the thickness of the stage, and remains in position when the substage is swung out. Stand, in Case, with Mechanical Stage 'A Eyepieces I in. (14 mm.) Object Glass, 32° .. I in. {4 mm.) Object Glass, 110" . . ^ij in. (2 mm.) Oil Immersion, 1*3 n.a Beclc Achromatic Condenser, 1" N.A. Dust-tight Triple Nosepiece .. 13 10 0 15 0 15 1 10 5 0 3 0 0 17 £25 7 6 Particulars Of Ra Ob U* BcCKj LtD., 68, Cornhill, LONDON, E.G. CANTOR LECTURES on the THEORY OF THE MICROSCOPE, by Conrad Beck, Price 1/-. DENT'S CLOCKS WATCHES AND CHRONOMETERS FOR 5CIENTtFIC USE. Sidereal or Mean Tiine Clocks for Observatories, £21 and upwards. THREE GRAND PRIZES AND ONE GOLD MEDAL FRANCO-BRITISH EXHIBITION. The only Grand Prize awarded to a British Firm for Watches, Clocks and Chronometers. The only Grand Prize awarded for Astronomical Rej^ulators, Chronographs, and Ship's Compasses. TRADE MARK CAUTION. 61, STRAND, and 4, ROYAL EXCHANGE, LONDON. Telephone So. 61 City. The Proprietors of SCHWEITZER'S " COCOATINA, " " FAIRY COCOA, " &c., beg to inform their clients that NONE of their products are manufactured in Germany ; that they are a private ENGLISH COMPANY man- aged by a Board of ENGLISH DIRECTORS; and that all shares are held by relatives and con- nections by marriage of the late sole proprietor^ Captain Thomas Edward Symons, R.N. — JOHN KING, •■ KlTowiedgl." — UXBRIDGE, SOUTHALL, AND EALING, is favourably equipped for the PRINTING OF SCIENTIFIC BOOKS, BROCHURES, &c., and will be pleased to submit Estimates. Address all Communications to 213, UxUrldge Road, Ealing, London, W. TELIPMONSi 1144 EaLINS. KNOWLEDGE. March, 1915. NEW Bauscfi '|om[» UNIVERSAL BALOPTICON This new Science Lantern is the outcome of many years' careful study in projection lantern construction, and offers many facUities to render projection of the various kinds successful in every way. The projection lenses and condensers are carefully chosen to suit the source of illumination and projection distances, in order to furnish well-defined and brilhant images of either opaque or transparent objects on the screen. The manipulation of this apparatus is the simplest possible, and the change from one mode of projection to the other only requires a few seconds. This apparatus is also arranged to be equipped for either Cinematograph Projection or Projection Microscope. It is a universal projection apparatus in the true sense, and has already met with great favour in many Scientific Institutions and Learned Societies. Price of the complete outfit, with vertical ^, _ _ ^ _ - _. attachment, and with projection microscope £44 15 1 O Same outfit, with vertical attachment, but ^,^^ g^ -^ without projection microscope £36 9 2 Demonstration of this Instrument will gladly be given in our New Demonstration Rooms by appointment. DESCRIPTIVE BOOKLET " Oi V.2 " (BALOPTICONS) ON APPLICATION. MICROSCOPES (over 100,000 sold), MICROTOMES, PHOTO-MICROGRAPHIC and DRAWING APPARATUS, CENTRIFUGES, GANONG'S APPARATUS for PLANT PHYSIOLOGY, VISCOSIMETERS, 4c. Also N.B ALL OUR INSTRUMENTS BEING MADE AT OUR OWN FACTORY IN ROCHESTER, N.Y., THERE WILL BE NO DELAY IN DELIVERY, AND WE HAVE JUST RECEIVED LARGE STOCKS. BAUSGH & LOMB OPTICAL CO., 37-38 Hatton Garden, London, E.G. Telephone : Holborn 2640 ] Op through all Dealers. [Telegrams: "Optibalcp, London.' Trade Makk. JAMES SWIFT & SON, Optical and Scientific Instrument Makers, Contractors to all Scientific Departmenti of H.M, GoT'trnnunt. Grands Prix, Diplomas of Honour, and Gold Medals at London, Paris, Brussels, &c. THE "DISCOVERY" MICROSCOPE AS supplied to tlie Royal Society (or llie Antarctic Expedition, the Priticipal Science Colleges, and Medical Schools. Fitted with first quality | in. and \ in. Objectives, Ocular and Iris Diapiiragm, In Cabinet, £6 : 15 : Oi Double Nosepiece and extra Ocular, 0 15 0 N3. — All otu Miixoscopes (indading the Lenses I are made in ooi own workshops on the Premises. Cata'o^ue post free. UNIVERSITY OPTICAL WORKS, 81, TOTTENHAM COIRT ROAD. LONDON. Microscope Slides. BOTANY - ZOOLOGY - GEOLOGY. LARGE STOCKS IN ALL BRANCHES. Slides prepared to order from Customers' own Material. See Catalogue "A,*' 40 pp. — Post Free to all parts. — PHOTOMICROGRAPHY. RECENTLY ISSUED NEW CATALOGUE. "B/la," Microscopes, Accessories, Reagents, and Apparatus generally. Post Free to Colleges, Schools, sad Regular Customers. FLATTERS & GARNETT, Ltd., 309, OXFORD ROAD ('K^:^;,;r), MANCHESTER. THE 'WILSON' SELF-RECORDING (Electrical) W RAIN GAUGE. Records automatically on a Weekly Chart wherever desired inside the house. SELF-REGISTERING AND SELF-RECORDING (ELECTRICAL) RAIN GAUGES. -«1 THE 'WILSON' SELF. REGISTERING RAIN GAUGE, With Improved Receiver to prevent splashing. SOLE MAKERS: PASTOR ELLI & RAPKIN, Ltd. Ci%':) ACTUAL MAKERS OF ALL KINDS OF METEOROLOGICAL INSTRUMENTS, Contractors to h.M. Government, 46, Hatton Garden, London, E.G. STANDARD INSTRUMENTS OF ALL KINDS. Illustrated Price List Post Free. *^* We pay carriage and guarantee safe delivery within U.K. on all our Instruments. Printed for the Proprietors (Knowledge Publishing Company, Limited), by John King, Ealing and Uxbridge. — March, 1915.