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and if the operation has been successfully carried out readily charged by allowing a rubbed sealing wax or the result will be as indicated in Fig. I B.
ebonite rod to spark to the outside wire. In measurIn this sort of work it is often necessary to make ing leaks the gold leaf should always be charged to sulphur stoppers, &c., of various shapes. To do this about the same extent, as the sensitiveness depends a it is only necessary to make paper models of the re- good deal on the amount of the deflection. The quired shape, into which the sulphur is cast. The instrument will not keep its charge indefinitely, but paper generally sticks to the sulphur, but may be will show a small leak even if no radio-active subtaken off with a clean knife without impairing the stances are present; this is nearly all due to the soinsulation. It is advisable to do this, and also any called spontaneous ionisation of the air. There is cutting away of the sulphur that may be necessary, practically no leakage across the sulphur if the instruimmediately after it has set, since it becomes very hard ment is properly made. and brittle soon afterwards.
For some purposes a more convenient arrangement For ordinary work with radio-active substances it is that indicated in Fig. 3, where the figure is drawn is not necessary to employ the most sensitive type of so as to exhibit the electroscope in its most sensitive electroscope, and for such work the design shown in form, i.e. with the minimum capacity. A piece about Fig. 2 is very convenient. It consists of a brass 4 cm. deep is cut off a wide brass cylinder, and the cylinder of about the proportions shown and 10 cm. side tubes fitted on as shown. The gold leaf is carried high. The top is closed by a flat plate with a narrow by the wire b, and is insulated by the sulphur bead a, tubular opening a, into which a sulphur stopper b, formed in the manner already described. Thus the cast as above, fits fairly tightly. The sulphur is best insulation leak can only take place to the support c, cast round the wire destined to carry the gold leaf. and can be entirely prevented by keeping c at the same For examining the properties of various radiations the bottom may be made in the form of a ring, as shown. This is fixed by the slot and pin indicated or some
similar arrangement, and the circular hole in the base
9 can be covered with sheets of foil, &c., if it is desired to examine the penetrating power of the rays under investigation. In all these instruments a hole has to potential as b by means of cells. The insulation of be cut in the metal both in front and behind the gold the wire c from the tube which supports it need not leaf to illuminate it and to read its position. The be of a very high order; it is sufficient to fix it in with holes are conveniently of about the relative size shown; a rubber stopper in the manner shown. So far we they may be covered up with glass, mica, or trans- have all our charged system enclosed, so that there parent celluloid, whichever is most convenient. A arises the difficulty of charging it. This is done by suitable illumination is obtained by placing a sheet of means of the wire d, which can be rotated about an white paper in front of a paraffin lamp about twelve axis through the centre of the ebonite stopper e. It inches behind the electroscope. The movement of the is advisable to remove the wire d from the gold-leaf leaves is most conveniently read by means of a micro- system when once this has been charged. By means scope of about 6 cm. focal length furnished with a of the sealing-wax handle f this may be accomplished micrometer eye-piece. It is advisable to have a micro- without discharging the electroscope. The instrument scope with as short a focal length as possible to in- is so far open. It is conveniently closed by two squares crease the magnification, and therefore the sensitive- of window glass cemented on to the brass cylinder ness.
with sealing wax. The whole of the outside is then The final appearance of the electroscope will de- covered with thin lead sheet or tin foil to obviate effects pend very niuch on the appliances at the disposal of due to the glass getting charged. Suitable windows the experimenter. An instrument of this character must be cut in this to allow the position of the gold could quite well be made out of a cigarette tin, but it leaf to be read. would probably be more satisfactory to have the metal The above arrangement is as sensitive as this type parts inade by a competent mechanic.
of instrument can conveniently be made, since its If cells are not available the above instrument is I capacity is only that of a short piece of wire and the gold leaf. Generally speaking, the capacity in electro- years of Dr. Bell's directorship, the field parties have static units is found to be of the same order as the been increased, and during the past year they have length of the wire. In this or a slightly altered form, worked in many interesting districts, from the Yukon the instrument is suitable for experiments on spon- and British Columbia in the west to New Brunswick taneous ionisation and the radio-activity of ordinary and Nova Scotia in the cast, and from southern materials.
Ontario and Quebec to Lancaster Sound in the Arctic In experiments on emanations, induced activity, and regions. Their researches have had reference to gold, very penetrating rays it is often convenient to increase silver, lead, copper, graphite, corundum and mineral the magnitude of the effects by allowing them to ionise pigments; to coal, peat, petroleum and natural gas; a large volume of air. For this purpose the arrange- to various building and ornamental stones, clays and ment last described is particularly convenient. It is cement ingredients. Hitherto unknown sections of the only necessary to solder a long straight wire upon the country have been explored and surveyed, and obserylower end of b and to fix g by means of a rubber ations have been made on the timber, soils, and water stopper into the neck of an oil can. The leak then supply, as well as on the general natural history. measured is due to the ionisation produced throughout The palæontological work of the survey has been the volume of the can. The sensitiveness, though carried on by the veteran palæontologist Dr. J. F. greater than before, is not increased in the ratio of Whiteaves, aided in the department of vertebrates by the volumes, as would otherwise be the case, owing Mr. Lawrence M. Lambe. In the “ Contributions to to the increased capacity produced by the additional Canadian Palæontology" (vol. iii.), recently issued by wire. This arrangement is especially useful for the survey, Mr. Lambe has described some remains of examining the induced activity which may conveniently the carnivorous dinosaur Dryptosaurus incrassatus be deposited on the wire.
(Cope), from the Edmonton series of Alberta, in the A still more sensitive type of electroscope was re- North-West Territory. The strata belong to the cently invented by Mr. C. T. R. Wilson.
Lower Laramie (Cretaceous) formation. The importhowever, appear to be an instrument which can be ance of a more intimate knowledge of the fauna of the safely recommended to the inexperienced, so that it Edmonton series is apparent when it is borne in mind scarcely comes within the scope of this article. It is that the beds of this series in Alberta constitute the described in the Cambridge Phil
. Soc. Proc., vol. xii. principal coal-bearing horizon of the district. P:. 135, and may be bought from the Cambridge Dr. Bell himself has been partly occupied, in conScientific Instrument Company. Much further in- junction with other leading geologists in Canada and formation about electroscopes and electrometers for the United States, in investigating the crystalline rocks radio-active work will also be found in Prof. Ruther-in Upper Michigan, in Wisconsin and Minnesota, and ford's book on radio-activity, chapter iii.
in the Rainy River, Thunder Bay, and other districts O. W. RICHARDSON. of Ontario, with the view of settling disputed ques
tions. The controversies on these rocks have long
been occupying attention without any definite result. GEOLOGICAL SURI'EY OF CANADA.
A few years ago Dr. Bell urged upon the International THE AE Geological Survey of Canada, which was Committee of Geologists the desirability of forming a established in 1842 under the direction of Mr.
small central committee, the members of which should (afterwards Sir) William E. Logan, commenced its go to the ground together and look at the facts. This labours with 1500l., which was voted by the Provincial
was carried out, and as a result the members have Legislature. The sum seems to have been granted
come to an almost complete agreement on all the vexed without any clear idea of the length of time which the points. The standing committee consists of Dr. Bell survey would take, but apparently it was expected to
and Dr. F. D. Adams (professor of geology in McGill last about two years.
University) for Canada, and Dr. C. W. Hayes (chief In the winter of 1844-5 the amount was expended,
geologist of the U.S. Geological Survey) and Prof. and Logan was more than 8ool. out of pocket.
C. R. Van Hise (president of the State University of Eventually provision was made for the continuance Wisconsin) for the United States. By invitation there of the survey for five years with an annual grant of were also associated with them Prof. Leith (of the 2000l. Notwithstanding many difficulties and dis
University of Wisconsin), Dr. Lane (State geologist appointments vigorous progress was made in the field of Michigan), Prof. Seaman (professor of geology in work and office work, and this has been continued the College of Mines at Houghton, Michigan), Messrs for upwards of sixty years under the successive
Sebenius and Merriam (geologists of the Iron Ranges), directors, Selwyn, George Dawson, until now, when
and Prof. W. G. Miller (provincial geologist of the survey, under Dr. Robert Bell, is provided for
Ontario). It is anticipated that the joint report will better than at any previous time. Thus the total votes
shortly be published. for the present financial year amount to 22,800l. for general purposes, and to about 8oool. for the salaries of permanent officers.
RECENT EXPLORATION IN THE MENTONE We gather from the last summary report by Dr.
CALES. Bell that while the Canadian Geological Survey, like PROE MARCELLIN BOLLE has recently been palæontological, zoological, botanical, ethnological, the Rochers rouges (Baoussé-roussé of local patois) and archæological investigations, by far the largest near Mentone, and read a paper on his results before proportion of the work has been of an economic and the Société géologique de France in the early part of practical character. Thus the justification for the in- last year, which is published in the society's Bulletin creased support given to the survey is amply supplied (No. 1). Since the original discovery by M. Rivière by the investigations which have been carried on with of a human skeleton in one of these caves, the question the view of aiding the development of the mineral re- of the age of their deposits has been debated with sources of the country. Up to the end of 1903 the much warmth, but without any satisfactory result. In publications of the survey included about 350 maps, of recent years the caves have been carefully and systemwhich 100 relate especially to mining districts; and atically explored under the direction of the Prince of about 250 reports and bulletins, amongst which nearly Monaco, with the result that a great number of fossils 100 are exclusively economic. During the four have been obtained. Prof. Boule's researches were
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