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MR. E. R. Pratt, of Ryston Hall, Norfolk, writes an River have been worked to a slight extent. A sample of interesting article on the East Anglian timber willow in laterite iron from Comet Vale, North Coolgardie, the recently published Journal of the Royal Agricultural proved of great interest on account of the occurrence in Society. The supply of timber suitable for their trade has it of a notable proportion of chromium, mostly in the form in recent years caused manufacturers of cricket-bats some of a hydrate. A large portion of the report is devoted to anxiety. In East Anglia, and apparently in other parts the results of examinations of the various goldfields, full of England, all large willows have been felled, except those reports of which will be published in due course. kept by landowners for ornamental purposes, and the price

The weather report of the Meteorological Office for the of timber good enough for bat-making has risen to 5s.

week ending Saturday, May 19, shows that the recent rains per foot. Two varieties of willow are purchased, the

were excessive in places, while in other parts of the United bark,” which is considered much the best, and the " open

Kingdom the rainfall was below the average. In the east bark." Growers of willows have found it a difficult matter

of Scotland and in the north-east of England the aggregate to ascertain what variety the bat-maker wants, as his

fall was at least four times the average. The measuredescriptions of the tree have been very vague. Mr. Pratt

ments due to the exceptionally heavy rains of Saturday, has gone carefully into the question of variety, and has examined a great many willows in the eastern counties.

May 19, were :-2.53 inches at North Shields, 2.40 inches

at Alnwick Castle, and 2.23 inches at Seaham. Both On the authority of a botanist who has given special atten

France and the Spanish Peninsula participated in the heavy tion to the genus (Rev. E. F. Linton, of Edmondsham,

rains of Saturday, the measurement for the twenty-four Salisbury), he states that the “ close-bark willow" is

hours at Lyons being 2.25 inches, and at Corunna 2.40 not Salix alba, but S. viridis, a variable hybrid between

inches. S. alba and S. fragilis. Many of Mr. Pratt's specimens closely approached the former species, but could always be We have received copies of the Boletim mensal of the distinguished by the bronze-red winter shoots. He believes Observatory of Rio de Janeiro, issued under the auspices that the genuine S. alba, of which he has cultivated speci- of the Ministry of Industry. Anyone wishing to study the mens obtained from Kew, is very rare in the eastern climate of that part of the Atlantic shore lying between counties. Mr. Pratt further states that the “open-bark the mouth of the Amazons and Rio de Janeiro will find willow " of the bat-maker is S. fragilis, the crack willow, trustworthy statistics for several of the coastal stations. or its variety, S. Russelliana, the Bedford willow. In his The data are chiefly for ten-day means, with monthly experience S. viridis is much more common in East Anglia means and extremes, but for Rio de Janeiro the actual than S. fragilis.

observations for three-hourly periods are given in addition,

and furnish most valuable details for all meteorological In the Engineering Review (vol. xiv., No. 5) illustrations

elements. are given of the works at Notodden where the synthesis of nitrates from the air has been found commercially The Republic of Uruguay has recently established a practicable.

National Institute for Weather Prediction, with its central

observatory at Monte Video ; the meteorological observatory Some very useful hints for horseback travel and transport

at that place was founded by the municipal authorities in are given in an article by Mr. F. L. Waldo on outfitting 1895. Observations have been made at several stations for for the prospecting trail in northern Mexico in the

some years, and the new institution has commenced its Engineering Magazine (vol. xxxi., No. 1). During a ten

operations by the collation and discussion of the means years' residence in Mexico the author's attention has

and extremes already available, and by the investigation many times been directed to the incongruity of the outfits

of the characteristics of the severe storms which affect the prepared and brought into that country by those whose navigation of the estuary of the Rio de La Plata. The business or pleasure call them into the Sierras. While

most dangerous storms are those from the south-east, as the suggestions given refer specifically to a certain region, they usually occur with a rising barometer, in connection many of them will be of value elsewhere.

with anticyclonic conditions over the Atlantic, and are freA BULLETIN (vol. iii., No. 54) has been issued by the

quently accompanied by thick fog on the coast. The first Department of Agriculture, Madras, describing experiments

number of the bulletin of the institute contains an exposi. on well irrigation made by Prof. A. Chatterton at Metro

tion of the hydrography of the estuary, and tables showsapuram in 1902–5. The results show that with adequate ing, inter alia, the effect of the various winds upon the

tides of the river. pumping power it is possible to improve the water supply and to cultivate a very considerable tract of land from

Two reports have recently been issued on rates of deck a single well. If in the future oil engines and pumps watches and of box and pocket chronometers on trial for are extensively used for well irrigation in India, it appears purchase by the Board of Admiralty at the Royal Observcertain that the 3-inch centriíugal pump will be most atory, Greenwich, in the latter half of last year. The largely employed, and that such a pump will water six number of deck watches on trial from August 5 to acres per day of twelve hours, and will be suitable for

November 25, 1905, was 125, and the makers of the first areas ranging from thirty to fifty acres.

five in the list, in which the watches are arranged in order The annual progress report of the Geological Survey of

of merit, are :-(1) W. Potts and Son, Leeds ; (2) L. Hall. Western Australia for 1905 (Perth, 1906) shows that much

Louth, Lincs ; (3) S. D. Neill, Belfast; (4) and (5) valuable work has been done. The Wodgina tinfield has J. Player and Son, Coventry. The makers of the first five been carefully examined, and it is believed that it will

box chronometers of those on trial from June 17, 1905, to prove an important tin and tantalite producer. About January 6, 1906, are :1) Kullberg, London ; (2) and (3) I cwt. of tantalite specimens have been presented to the

Johannsen, London ; (4) Lilley and Son, London ; (5) M. F. Survey museum. During the year there was a sudden Dent, London. In the same period the makers of the demand for tantalum ores which had hitherto been con. leading five pocket chronometers are :--(1) Newsome and sidered useless. Considerable interest has been taken Co., Coventry ; (2) and (3) Kullberg, London ; (4) Lindqvisi, locally in deposits of graphite, and those on the Donnelly London ; (5) Newsome and Co., Coventry.

are

as

PROF. B. WALTER states in a brief note published in the field"; he also gives reproductions of his spectrograms, Annalen der Physik (vol. xix., p. 874) that the ultra-violet with wave-length scales, for the region between 1 1670 portion of the spectrum of a high-tension arc in air shows

and a 1270. a series of bands identical with those observed by Eder in 1842 as characterising the combustion of ammonia, and

THE Watkins Meter Co., Hereford, has published a third

edition of considered by him as ammonia bands. It would appear

The Watkins Manual of Exposure and Developprobable that these bands are to be attributed rather to

ment," by Mr. Alfred Watkins. an oside of nitrogen, produced in both cases, than to the The report for the year 1905 of the council of the Hampfaus suggested by Eder.

stead Scientific Society has been received. The Christmas

juvenile lectures, and those on nature-study, intended to Sove successful attempts, made in the geophysical labor

encourage the teaching of this subject to children, proved atory of the Carnegie Institution, to prepare small plates

very successful. Among lectures delivered at the general of quarts glass suitable for the construction of lenses,

meetings of the society may be mentioned those by Prof. mirrors, or other optical apparatus, are described by Marcus Hartog, on the end and beginning of individuality Messrs. Arthur L. Day and E. S. Shepherd in Science

as shown in the living cell ; Dr. R. S. Clay, on the peculi(vol. xxiii., No. 591). The glass obtained was nearly free

arities and paradoxes of fluid pressure ; Sir Samuel Wilks, from air bubbles, and was only slightly discoloured by the

F.R.S., on spirals; Dr. C. W. Andrews, F.R.S., on fossil presence of silicon. The conditions for obtaining such a

hunting in the Libyan Desert; and Mr. F. W. Rudler, on the material br the fusion, in a small graphite box, of pure geology and scenery of the British Isles. cristallised quartz

or tridymite, summarised follows:- :-an initial temperature of 2000° or more without The seventy-second annual report of Bootham School pressure. so as to allow of the production of sufficient (York) Natural History, Literary, and Polytechnic Society vapour to drive out the air between the grains, followed

shows that the pupils of this school continue to receive by pressure (at least 500 lb.) and a reduced temperature every encouragement to devote their leisure hours to the of about 1800', with time for the quartz to flow compactly

outdoor study of natural phenomena. During 1905 the together without being attacked by the graphite.

boys were particularly successful in discovering rare plants,

and though we have been unable to find a specific caution As interesting contribution to the study of Auorescence

in the report, we trust that all observers are urged not is contained in a paper published by Mr. Harry W. Morse to uproot plants or in any other way to assist the disin the Proceedings of the American Academy of Arts and appearance of rare species. It is satisfactory to find that Sciences (vol. xli., No. 27) under the title “ Studies of attention is given to many branches of natural science so Fluorite." The fluorescence and thermoluminescence of that the predilections of as many boys as possible may be Ruorite and the nature of the gaseous and liquid in- satisfied. clusions in fluorspar are dealt with under different headings. The fluorescence spectra shown by fluorite when excited by the light of the condensed electric spark between

OUR ASTRONOMICAL COLUMN. electrodes of certain metals contain sharp lines and narrow SPECTRUM OF Nova AQUILA No. 2.-A visual observation bands; the lines of these fluorescence spectra do not appear of the spectrum of Nova Aquila No. 2, made at the Lick to belong to any known substance, and are remarkable Observatory on September 5, 1905, showed a number of inasmuch as different lines are obtained with different bands, the brightest of which was recognised as HB. exciting sources. The spectrum also varies sharply from

Hy and a band near ^ 4600 were distinguished with crystal to cristal with the same means of excitement. The

difficulty owing to their extreme faintness.

Photographs obtained with the one-prism spectrograph cause of fluorescence, whatever be its nature, is removed

on September 6 and 10 (exposures three and four hours of destroved by heating at a temperature of about 300° C. respectively) confirmed the visual observation, the intensiAt the same temperature the colouring matter of the ties of the bands at 1 4600 and Hy being respectively onediferent varieties of fluorite is destroyed ; the nature of

fifth and one-tenth that of HB. H8 was also seen, but this colouring matter is discussed by reference to the

was very faint. gaseous products liberated at higher temperatures.

A faint continuous spectrum was seen to extend from As

about 1 4500 to the region of the Hy band. He and the these consist of hydrogen, carbon monoxide, and carbon so-called nebular lines were not visible. dioxide, the colouring matter would appear to be organic Visual and photographic observations made on October in its origin; the gases are probably produced by its under- 11, 1905, agreed in showing a marked diminution in the going a process of destructive distillation

brightness of HB, which was then no brighter than Hy

(Astrophysical Journal, vol. xxiii., No. 3). No. 3. vol. xxiii., of the Astrophysical Journal contains

A number of magnitude observations of this Nova, made

on various dates between September 20 and November 24 35 important paper by Mr. Theodore Lyman on the extreme at the Utrecht Observatory, are recorded in No. 4089 of ultra-violet spectrum of hydrogen. Part of this spectrum the Astronomische Vachrichten by Dr. A. A. Nijland. was previously photographed and investigated by Dr.

STEREO-COMPARATOR DISCOVERIES OF PROPER MOTIONS.Schumann, whose work was briefly described in vol. Ixix. At a meeting of the Paris Academy of Sciences, held on (p. 202) of XATURE. Uniortunately Dr. Schumann, May 7, Prof. Loewy announced that Prof. Max Wolf had although he photographed the spectrum down to 1 1270,

met with considerable success in discovering and measurwas urable to give the wave-lengths beyond ^ 1850, but

ing stellar proper motions by means of his this omission has now been rectified by Mr. Lyman, who

comparator.

In one instance a star of known proper motion was seen his sit only determined the missing wave-lengths, but has to be obviously displaced after the very short interval of also extended the known spectrum down to 1 1ozo (see I four years. When the two photographs, taken at this NATURE, P. 463, vol. lxix., and p. 110, vol. Ixx.). In the interval, were placed in the stereoscope, the star in ques. prryt piper the author describes the apparatus and

tion was seen to stand out in a plane considerably different methods employed in great detail, " in the hope that an

from that in which the neighbouring stars appeared to be exact knowledge of the conditions necessary to

Prof. Wolf has also been able to show that a ninthmay prose of value to investigators who work in this magnitude star in the constellation Leo has a proper

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motion hitherto unsuspected, and he has obtained a value in some respects from the former, are therefore or great for the motion which he believes to be more correct than value and interest, and may be quoted in full. could be determined by ordinary micrometric measures. • The okapi here is generally found singly or in pairs, In this case a period of fourteen years separated the times but Mobatti hunters state that sometimes three may be of taking the photographs (Comptes rendus, No. 19, 1906). found together. An essential to the life of the okapi is a MEASURES DOUBLE

small stream of water with some muddy and swamps

MULTIPLE STARS.-The measures of 1066 double and multiple stars are published ground on either side. In this grows a certain large lesi in vol. ii., part iii. (astronomical series), of the Publica

that on its single stalk attains a height of 10 feet. It is tions of the University of Pennsylvania by Prof. Doolittle.

the young leaf of this plant that is the favourite food of The made with wire micrometer

the okapi, and I venture to say that where the plant is attached to the 18-inch refractor of the Flower Observ

not to be found the animal will not exist. During the atory, and include, among others, 733 Burnham stars,

night he will wander along in the mud and water in search 109 02, and 102 stars, Four hundred and ninety-two

of it. Here he may be found feeding as late as 8 a.m. in stars from Prof. Hough's catalogue have also been re

the morning, after which he retires to the seclusion of the measured but are not included ; it is Prof. Doolittle's inten

forest, where he remains until nearly dusk. On the three tion to re-measure all the stars discovered by this observer.

occasions that I was at close quarters with the beast, he The micrometer, the corrections of the instrument, and

was perfectly concealed in this swamp leaf. Near the River the method of observing are all fully discussed in the

Welle I found his spoor on ground frequented by buffalo present publication, which is a continuation of part iii.,

and waterbuck, but this is unusual, and his companions vol. i.

in the forest are the elephant, the greater bushbuck, the Partii., vol. ii., of the same publications gives the

yellow-backed and small red duikers. The okapi is very results of the observations made with the zenith telescope quick of hearing, and in that respect is classed by the of the Flower Observatory from October

Mobatti with the bushbuck (local name bungana "). In

1901, to December 28, 1903, and also contains a re-discussion of

the forest here I consider this latter beast to be more the 1896–1898 series, of which the details appeared in

difficult to obtain than the former. On the hunting ground part ii., vol. i., in 1899.

of the first village that I visited I estimated the number of

okapi as five or six, at the second and third nil; and OBSERVATIONS OF COMET 19050.-Numerous observations twenty miles south in the forest, on very likely ground of comet 1905c are recorded in No. 4090 of the Astronomische Nachrichten.

where my guide said they were formerly numerous, there This object was observed at Vienna from December 17,

was one only, probably owing to rubber-collectors who had

been there. 1905, to January 14, 1906, and during that time its apparent Several specimens had been speared, shot, or trapped by diameter increased from 2' to 4'-5', the length of its natives shortly before the date of Captain Alexander's tail from 5 to 40', and its total magnitude from 9.5 to 4.0. visit, but time did not admit of further investigation. The On December 30 a nucleus of magnitude 6.0 was observed. sex of the new specimen is not stated, but it is to be hoped

Heliometer observations at the Cape Observatory showed that it will prove to be a male, as Sir Harry Johnston's the comet as a faint nebulous mass with no visible nucleus. example, now exhibited in the Natural History Museum, is Observations of position were recorded from February 5 a female. A pair of okapis are exhibited in the Congo to February 20, 1906.

Free State Museum at Tervueren, near Brussels, which The observations at Strassburg Observatory extended over the period December 10 to March 21, and the apparent

also possesses other skins; and there are likewise a few

other examples in Europe, notably one in Italy and another position, the total magnitude, and the diameter were re- in Mr. Rothschild's museum at Tring. It is a great corded on eleven different dates.

pity that the Belgian Government does not take immediatr A LUNAR TIDE ON LAKE HURON.-Whilst examining the

steps to publish coloured figures of its specimens in curves showing the periodical oscillations of the seiches order to aid in solving the question as to whether there on Lake Huron, Prof. W. J. Loudon, of Toronto l'ni- is more than one species (or race) of okapi. Important versity, was struck by the regularity of their general out

information this point will, however, doubtless be line, which seemed more marked in calm weather. Further

afforded by the Alexander-Gosling specimen, which, it may investigation of the matter showed a well-marked and be hoped, will also indicate (if a male) whether the tips of regular rise and fall twice a day, and also showed that the horns always protrude through the skin, and thus for no oscillation of the lake could have a period of more than

shadow the antlers of deer. four hours.

From these facts Prof. Loudon concluded that a true lunar tide occurs on Lake Huron, a conclusion which his THE TARAWERA VOLCANIC RIFT, NE further experiments seemed to verify.

ZEALAND.

MR. JAMES MACKINTOSH BELL, director of the THE HAUNTS OF THE OKAPI.

New Zealand Geological Survey, contributes a paper

to the April number of the Geographical Journal describing ACCORDING to a report in Monday's Times (May 21) the present topography of the great volcanic rist of

the expedition to the Congo Free State under the Tarawera, in the north island of New Zealand, and the charge of Captains Boyd Alexander and C. B. Gosling has changes which have taken place in the configuration of the been successful, not only in procuring a fine skin (and it region since the great eruption of Mount Tarawera on may be hoped a skeleton) of the okapi, but likewise in June 10, 1886, which is memorable for the destruction of obtaining some important particulars with regard to the the famous pink and white terraces, and their submergence habits of this animal. The specimen, which it is stated in Lake Rotomahana. will ultimately find a home in the Natural History Branch Mount Tarawera lies near the centre of the Taupo of the British Museum, was obtained at Bima, on the River volcanic zone, and about 135 miles south-east of Auckland. Welle, in the northern territory of the Congo State. It This zone, which has a breadth of some twenty-five miles, is mentioned in the letter that the animal was seen alive extends from near the great volcanic cones of Ruapehu, by the expedition, but further particulars on this point are Tongariro, and Ngaurahoe north-eastwards White desirable, as it is not stated whether anyone but the Island, on the Bay of Plenty, a distance of nearly 160 miles. Portuguese collector by whom it was trapped had this A great rift, which was the scene of greatest intensity of good fortune. The animal was caught in a pit according the 1886 eruption, stretches from near Lake Okaro along to native fashion, previous attempts to shoot it having the Tarawera range to Mount Wahanga, in the most northproved ineffectual.

easterly part. This rift, really a line of craters, forms a Hitherto the only definite account of the kind of country huge fissure about nine miles in length, cutting the summit inhabited by the okapi and the probable nature of its food of the range, and appearing on its south-western slope. is one given by Mr. J. David under the title of “ Weitere It is divided into several somewhat distinct craters by low Mitteilungen über das Okapi," and published in vol. lxxxvi. partitions, and on the south-west side a long narrow rift of Globus (1904). Captain Alexander's notes, which differ extends to the base of the hill, so far as the edge of Lake

on

to

Mud, sand, and immense The author shows that the flow of water in a given

course

а

Rotomahana. Lake Rotomahana is a sheet of dirty, are being made as to the movement of underground water. muddy green water, some three and a half miles long by A further paper on this subject has now been issued as less than two miles in the opposite direction, and with a the result of investigations made by Prof. Slichter, No. maumnum depth of 427 feet. In continuation along the 140, on field measurements. same line, beyond Lake Rotomahana, are the deep holes This paper presents an amplified exposition of the forming the Black, Fourth, Waimangu, Inferno, Echo | method of measuring underground water as described in Lake, and Southern craters. Hot water and steam issue his former paper of 1902. It contains descriptions of the in larger or smaller quantities from these craters, the apparatus used for the laboratory study of wells controlling water finding its way to Lake Rotomahana.

horizontal and vertical movements, and the result of these The most remarkable feature of the region during the studies confirms the conclusions described in the former last few years has been the great geyser of Waimangu. i paper as to the possibility of measuring the flow of subI his gryser was discovered in January, 1900, and is believed surface water with trustworthy accuracy. Some improveto have become active only a short time before that date. ments that have been made in the apparatus as the result While playing, outbursts occurred nearly every day, and of experience are described. sometimes more frequently. boulders were shot up in huge columns of dirty black direction through a column of sand is proportional to the water. At some hundreds of feet above the water the difference in pressure at the ends of the column, and telumn broke, showering, boulders, mud, and sand back inversely proportional to the length of the column, and is into the pool, and even high up on the walls surround-! also dependent upon a factor which he terms the transing it.

mission constant of the sand. In July, 1904, the great geyser suddenly ceased, and Experiment shows that the resistance to the flow of remained dormant for seven weeks and five days; then it water through sand is very great, the water having to

pass through pores, usually capillary in character, and the diameter of which varies from one-fourth to one-seventh of the diameter of the sand particles. When the sand is not of uniform size, and is mixed with grains slightly larger, the effect is to increase the capacity of the sand to transmit the water. Where particles seven to ten times the diameter of the original sand grains are added, each of these tends to block the

of the water. For example, a boulder placed in

mass of fine sand checks the passage of the water, and the rate of flow decreases in proportion to the number of such boulders until the amount of the large particles is equal to about 30 per cent. of the total

After this the flow increases until the mass of fine particles becomes negligible, and the capacity to transmit approaches that of the mass of large particles alone.

These facts are shown to have an important bearing upon the capacity of gravels

to furnish water to wells, or Fig. 1.-Highest known eruption of Waimangu.

to transmit it in the under

flow to rivers. again burst into action, and until November 1 following Tables are given showing the transmission constant for outbursts occurred almost daily. Then it stopped, and since sands and gravels of different sizes and different degrees then there has been no further explosive activity. We of porosity. reproduce a photograph of the highest known eruption of It is also shown that the rate of flow is affected by Waimangu, from the illustrations accompanying Mr. Bell's temperature, a change from freezing point to 75o nearly paper. It is estimated that this “ shot” ascended 1500 feet' doubling the power of the soil to transmit water.

This above the water, and carried a volume of 800 tons.

paper contains a great deal of information as to the dis

charge from wells used for irrigation or other purposes. HYDROLOGY IN THE UNITED STATES.

Paper No. 144, by Mr. Daniel D. Jackson, deals with

the normal distribution of chlorine in the natural waters THE papers relating to the hydrological work in the of New York and New England. The author shows that,

L'nited States which are issued by the department of with the exception of local deposits, the normal chlorine in the Geological Survey have from time to time been noticed

natural waters is derived from the salt of the ocean, blown in NATURE. We have now to acknowledge twenty-six of over the land by storms, and that it diminishes in amount the papers last issued. The greater part of these relate to as the distance from the ocean increases. This decrease is the progress of stream measurements in the different

so definite that equal amounts of chlorine are found along States, and to other matters which are of local interest.

lines generally parallel to the sea coast, thus affording a There are, however, some of the papers that deserve the basis for the establishment of isochlors. Charts and tables allention of those engaged in works of water supply. I are given showing the proportion of chlorine at different

On a previous occasion, in VATURE of December 21, distances from the coast. The samples were taken from 1905. we gave a short account of the investigations that ponds or open water basins as far removed from human

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habitation as possible. The charts show that the quantity would rather seem that in this case they have fulfilled a of chlorine near the coast amounts to 6 parts in a million, necessary duty, and discharged an honoured trust. It has at 4 miles away to 5 parts, at 20 miles to 3 parts, always seemed to the writer that the ancient authorities at 40 miles to i part, and at 100 miles to 0-4 part.

at Greenwich were a little wanting in patriotism and The fact that chlorine exists in rain water to a large enterprise in entrusting to a foreigner, however eminent, extent near the sea coast was stated in the report on the reduction and discussion of Bradley's observations. domestic water supply of the Rivers Pollution Commission Groombridge's observations, in a sense, may not be so in 1874. It was there shown that on the coast of Devon- completely a national possession as those of Bradley, but shire, where with south-west winds sea spray is blown over certainly it is not unfitting that at the Royal Observatory, the land, the amount of chlorine varies from 1.20 to 2·10 almost within the shadow of which Groombridge erected parts in 100,000, and at the Land's End, with a strong his transit circle, his observations should be examined and south-west wind blowing, it amounts to as much as 21.8 discussed. parts. Inland the average quantity of chlorine diminishes to There are several circumstances which tend to give dis0.39 part; increases to 0.99 part at Liverpool and 0.79 part tinction to Groombridge's work. At the beginning of the at Newcastle.

last century his instrumental equipment was equal to, if Paper No. 151, by Mr. Marshall 0. Leighton, deals more powerful than, that of any other observer in with the field assay of water, and describes the methods Europe. The fact that, as an amateur, he gave his time which have for some time been used in connection with the and leisure to the repetition of the same mechanical per. investigations into the quality of water in various parts

formance shows that he was a lover of order and accuracy. of the United States. The methods described relate, not

Pond, the Astronomer Royal, whatever his failings may to laboratory experiments, but to simple tests to ascertain have been, appreciated the necessity for certainty and the general character of the water by methods which can

accuracy, and he must have impressed these qualities upon be carried out on the spot. These field determinations give Groombridge. Further, the lapse of time, that factor the turbidity and colour of the water, the presence of

which has increased the value of so much astronomical chlorine, carbonates, calcium, and iron, and the amount

work and enhanced the reputation of so many worthies, of hardness; also the amount of suspended matter. The

has fought on the side of the retired West Indian merchant. former are more particularly required in water for domestic

The method to be pursued in the reductions, how far supply, and the latter for that used for irrigation purposes.

the observations are to be treated as independent, how far The amount of gradient to be given to a canal for con

they are to be regarded as differential, are points which veying water for irrigation is governed to a great extent

must be left to the decision of the computers. They must by the solid matter in suspension, and this also affects

accept the entire responsibility, since the knowledge and the capacity of the storage reservoirs. The method for experience is theirs. In this case it is not impossible but

that they have had the assistance of tradition, The determining turbidity, accompanied by an illustration of the gauge used for this purpose, was given in NATURE of interesting remarks of Colonel Colby and Dr. Firminger January 7, 1904. A description and illustration of the

quoted by the revisers, probably do not exhaust the inform. Geological Survey field case is given in the paper.

ation at their disposal. It would be an impertinence for Paper No. 143, by Mr. J. H. Quinton, details the experi, criticism on the methods employed by those who have

anyone who has not even seen the originals to offer any ments made under the direction of the Reclamation Depart- gained familiarity and experience by long contact with ment on steel concrete pipes for the purpose of determining Groombridge's figures. These methods are described with the durability and permanence of these structures in connection with the supply of water for irrigation purposes.

clearness and in sufficient detail, but the revisers must The pipes experimented on were 5 feet in diameter, 20 feet

know so much more than they can set down. long, and 6 inches thick, of concrete, enclosing an armour

The result is to obtain a catalogue for the equinox of of steel rods sufficient to resist a head of 150 feet of water

1810 of 4239 stars. The number in the original Groomwith a factor of safety of 4. The experiments showed the rejected on various grounds, and five have been added as

bridge catalogue was 4243, but of these nine have been difficulty, even with the closest attention to the construc

separate stars. The places of a few more stars have been tion, of making pipes of this kind that would stand a head

considered discordant, and have not been used in the subof 100 feet.

sequent discussion of proper motion. The accuracy of the Paper No. 150, by Mr. Robert E. Horton, gives the catalogue and the care of the observer can both be estimated results of an investigation of the theory of weir measure- in some measure from the fact that a discrepancy, of four ments, and the discharge over different forms of weirs. seconds of arc in either right ascension or polar distance The various coefficients of Bazin, Fteley, Stearns, and Hamilton Smith are analysed. A further description is

has been considered a proper limit 10 warrant the exclusion

of the observation. The number excluded is 75 in right given of the experiments performed at the Cornell Uni- ascension and 214 in polar distance, slightly more than versity laboratory, where a closely regulated volume of

I per cent. of the total number of observations. was passed over weirs of different forms placed

The peculiar value of this catalogue lies in the fact that across an experimental canal, and the results obtained com

its epoch is 1810. Therefore, by comparison with modern pared with the different formulæ for obtaining the dis- observations, it offers the means for a new determination charge. Tables are also given for calculating the discharge of the precessional constant, while the new proper motions over weirs.

which it makes available should give greater certainty to researches into the amount and direction of the solar

motion. The length of time elapsed since Groombridge's GREENWICH OBSERI'ATIONS.1

day is not much less than that available in the case of

Auwers-Bradley, and the accuracy of the observations would IN the introduction to the first work, mentioned below, an opinion is expressed that the revision of an old cata

seem to be of the same order; but Bradley's optical means logue must always be a source of anxiety to those who

were smaller, and the average of his stars considerably advise and undertake the revision, and that only the final brighter. Groombridge's stars include many of the ninth result can justify the expenditure of the time and labour.

magnitude, and fill a gap between those to which Bradley's Those who are responsible for this work need be under

observations refer and the results that will be derived from no apprehension that their efforts have been misspent. It photography: On the other hand, Bradley's stars were

better distributed over the whole skyGroombridge limited 1 “New Reduction of Groombridge's Circumpolar Catalogue for the his observations to the circumpolar regions. Against this Epoch 1810-o." By F. W. Dyson, F.R.S., and W. G. Thackeray. Under the direction of Sir William H. M. Christie, K.C.B., F.R.S., Astronomer.

drawback, as against many others, the Greenwich authori. Royal. (Published by order of the Board of Admiralty in obedience to

ties have struggled with apparent success, and a few of His Majesty's command. Edinburgh: Neill and Co., Ltd., 1905.) Price their final results may be given. Telegraphic Determinations of Longitude made in the years 1888-1902,

We have, in the first place, the proper motions of more under the direction of Sir W. H. M. Christie, K.C.B..F.R.S , Astronomer

than four thousand stars determined by comparison of Royal. (Published by the Board of Admirally in obedience to His Majesty's places at intervals of approximately ninety years. These command. Edinburgh: Neill'and Co., Ltd., 1906.) Price 155.

proper motions have been derived for the most part by a

water

a

245.

64

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