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points a and d are connected by n passing over its third contact.
The points b and c are also joined to B and C, the former through the condenser 2. When the key T is closed this condenser is charged to the difference of potential between B and C, the charge passing through the blade m and leaving the galvanometer at rest. When the switch is thrown over to the third point, A and D are connected, which practically cuts P and Qout of the circuit, leaving only the battery and R. With this shorter circuit the condenser is charged to the difference of potential between A and C (since D, B and A are all at the same potential) and if this is the same as that formerly existing between B and C there will be no change in the charge and, therefore, no deflection of the galvanometer which, for this position of the switch, is not short-circuited. As the switch is moved further the galvanometer is short-circuited again before the connection ad is broken, thus eliminating the back kick of the galvanometer as the charge in the condenser returns to its former value.
Having set up the apparatus as indicated in the figure, the manipulation is as follows: The key T is closed and the switch quickly moved from e to c. If there is a deflection of the galvanometer the key is opened, the switch set back to its first position, and the values of P and I changed until zero deflection is obtained when the switch is thrown. The arrangement is then 'balanced' and X=RQ/P.
This relation is easily deduced. The potential to which the condenser is charged in the first case, viz., that between B and C, is
E(R+P) e=I(R + P) = 7
1 R +P+Q+X .
and n, pivoted at b and d and both moved by the connecting piece, l, over a series of four contact points. Thus, used as a two-pole switch, b and d can be connected to any one of four different circuits; but in the present case only a few of the contacts are utilized, and these are connected so as to make and break the various connections in the order desired as the switch is quickly moved from one side to the other.
The arrangement then is as follows: The cell, or other resistance to be measured, is joined in series with three resistances, R, P and Q, Fig. 4. The points A and D are joined to a and d, and are connected whenever n rests upon the third contact point. The galvanometer is joined to the points b and c, while c and e are permanently connected, thus shortcircuiting the galvanometer when contact is made on either point, but when m is moved from e to c the short-circuit is raised for an instant. It is during this instant that the
The following results were obtained from a
large ‘Gonda' cell, a porous cup type of Lewhich readily gives the relation
clanche cell. It had been in constant use in
the laboratory for five months with no change X=R
of electrolyte. As it polarized rapidly for
the first ten seconds after closing the circuit It is true this result appears in the same
through one or two ohms, its resistance was form as that deduced for the Wheatstone
measured with values of R of 40, 60 and 80 bridge, but beyond a superficial analogy there
ohms. The values obtained were as follows: is nothing in common between the two methods. The Wheatstone's bridge method con
Resistance of 'Gonda Cell.' sists in dividing two parallel circuits in the
R= 60. R= 80. same ratio. Mance's method, on the other hand, consists in subtracting from the two
1.392 portions of a single circuit such resistances
1.384 that the two portions shall still maintain the 13.02
1.392 1.388 same ratio to each other. In this connection it may be of interest to
The average of these twelve determinations look at the results of a few measurements by
is 1.389 ohms, and the mean variation from this method. The resistance measured con- this
this value is 0.002 ohm, while the probable sisted of a medium-sized storage cell in series error of this result is 1 part in 2,600. with a coil marked 62 ohms.' This gives a But it is not my present purpose to discuss definite resistance with an E.M.F. not easily
experimental data except in so far as it shows polarized. The results of thirty measure
that Mance's method is not without some ments are shown in the table below. R was
merit. It has been shown that this method is varied from one ohm to forty ohms, and P
fully as accurate as is required for laboratory was given such values that Q would be a little
use, whether the resistance to be measured be over 4,000 ohms. Each balance was sensitive
of the first or second class. The purpose of to a change of 1 ohm in Q, and often the 0.5
this paper will be fully attained if it has ohm coil was used. The results are tabulated
clearly shown the principle underlying this I the order obtained, reading across the table method, and pointed out the very obvious error from left to right. As the room became which has crept into many of the text-books
r the resistance grew larger, each col- from Maxwell down to the present. umn showing the same increase of 0.002 ohm.
Arthur W. Smith. It is seen from these results that the method
PuiYSICAL LABORATORY, is as sensitive as a post-office box, and by
UNIVERSITY OF Michigan, using a larger condenser the sensitiveness can
Axy ARBOR, MICH., be still further increased.
February 11, 1905. From this limited data it is hardly safe to draw a general con
ORGANISMS ON THE SURFACE OF GRAIN, WITH clusion, but it may be noted that the smaller SPECIAL REFERENCE TO BACILLUS COLI.
of R, in other words, the larger cur- The recent note by Dr. Erastus G. Smith of X, the same as with ordinary cells.
on the occurrence on grain of organisms resembling the Bacillus coli communis' appears to warrant preliminary publication of some of
the results of my studies of the micro-organRoom.
R=1. R=2. R-3. R-4 R = 10. R = 40. isms normally present on the flowers and 12.°0
fruit of certain plants in the Piedmont region 12.06 13°0
0290 2.0305 2.0310 2.0315 2.0320 and the rice belt of South Carolina. These 2.0297 2.0315 2.0312 2.0315 2.0320
Tempera- | ture of
Resistance of 12 Ohms' Plus Storage (ell.
12.0265 2.0280 . 0905 2.0295 2.0300 2.0300
2.0265 2.0290 2.0305
studies, originally undertaken as a side issue 0 2.0315 2.0315 2.0317 2.0320 2.0302 2.0315 2.0315 2.0317 2.0320 SCIENCE, May 5, 1905.
in another problem, have proved intrinsically interesting.
In the fall of 1903 I determined the organisms present on the grain in twelve rice fields. In 1904 I studied both the flowers and grain in eight of the twelve fields examined the year before, and in four other fields. In 1904 I also studied, for comparison, the flowers and grain in eight wheat fields, and six oat fields; also the flowers and fruit in three peach orchards, flowers and fruit in two asparagus patches, and flowers and fruit in one patch of the wild Iris verna L. A few comparative studies of organisms on the fruit or flowers and the leaves of the same plant were also made. In every case exactly fifty grains or flowers or fruits, as the case might be, were taken at random from each field or patch, in the case of the cereals only one grain from any one spike. Each one was shaken in sterile water, allowed to stand for about an hour, shaken again, and the whole added to sterile agar-agar and plated; except in the case of peaches, when only a portion of the water was plated. The resulting organisms were studied in greater or less detail, according to their interest.
A part of the conclusions to date are as follows:
1. An immense but variable number and variety of micro-organisms were nornially
the same locality, and showed no constant association with the host plants studied.
2. Without exception, the same organisms that occurred on the flower could later be found on the fruit, but not in the same quantity. But organisms commonly occurred on the fruit that were not found on the flower.
3. The most constantly present organisms were certain yeasts; in greatest number and variety on the peach, asparagus and iris; but yet characteristically present on the cereals.
4. The bacteria on the flowers and fruit were not different in kind from those on the leaves of the same plant, nor, so far as studied, materially different in number, area for area. With the peach, asparagus and iris fungi, and especially yeasts, occurred in noticeably greater number on the flower and fruit than on the leaf.
5. Bacteria giving the standard reactions of the colon group were found in thirteen out of the sixteen rice fields examined, five of the eight wheat fields and all of the oat fields. All three peach orchards and both asparagus patches exhibited coli forms in both flower and fruit; but none were found on either flower or fruit of Iris verna. In the following tables are shown the proportion of flowers and fruits each flower or grain in the cereals representing a spike) found to have coli forms on the surface:
the time the plates were made. In the other Greece, IIungary, India, Italy, Japan, Mexico, fields the source of the coli forms was without Natal, the Netherlands, New South Wales, doubt the excrement deposited by draft-ani- New Zealand, Norway, Queensland, Sweden, mals in working the ground, to say nothing Switzerland, the United Kingdom and the of that deposited on the banks and adjacent United States. It was then unanimously resecluded spots by workmen. Indeed, the non- solved to compile and publish a complete cataoccurrence of coli forms in certain fields seems logue of current scientific literature, arranged most difficult to explain.
according to both subject matter and authors' These studies are being continued, and names. The Royal Society was requested to when completed, will be published probably appoint a committee to further consider the in the Centralblatt für Bakteriologie.
system of classification to be adopted and
HAVEN METCALF. other matters, and it was decided to establish CLEMSON A. & M. COLLEGE,
the central bureau in London. SOUTH CAROLINA.
At the second international conference held
in London on October 11 to 13, 1898, several THE INTERNATIONAL CATALOGUE OF
questions were settled and a provisional interla SCIENTIFIC LITERATURE.
national committee appointed which afterIn 1903 I was appointed by the council wards met in London, on August 1 to 5, 1899, of this society acting as the regional bu- when the work was still further expe reau for New South Wales, to represent this the Royal Society requested to organize the state at the council meetings held in London central bureau and make all necessary arrangein May last. I duly attended the meetings ments so that the preparation of the catalogue and now have the honor to make the following might be commenced in 1901. report. The Royal Society of London com
A third international conference was held menced the work by compiling catalogues of in London, on June 12 and 13, 1900, at which scientific papers (printed between 1800 and all financial and other difficulties were removed 1883) in twelve large quarto volumes, the by the Royal Society agreeing to act as pubfirst volume of which was issued in 1867. In lishers and to advance the funds necessary to it the titles are arranged solely under the au- start the enterprise. The supreme control thors' names. A catalogue of the papers pub- over the catalogue is now vested in an interlished since, i. e., between 1884 and 1900, is national convention which is to meet in Lonnow in hand, and a subject index is also nearly don in 1905, in 1910 and every tenth year completed.
afterwards, to consider and, if necessary, to The possibility of preparing a complete cata
revise the regulations for carrying out the logue of current scientific literature was con- work of the catalogue. In the interval besidered by the Royal Society in 1893, but as tween two successive meetings of the convenit was apparent that the work was beyond the tion the administration of the catalogue is resources of the Royal Society, or indeed of carried out by the international council, the any single body, the society sought the opin- members of which are appointed by the reion of representative foreign bodies and in- gional bureaus. dividuals, and the replies being favorable, steps. The total expenditure from July 1, 1900, to were taken to summon an international con- February 29, 1904, has been £10,153, and the ference. This conference, at which I was pres- . total amount received from subscribing bodies ent as a delegate, took place in London, on was £6.755; eventually the publication will pay July 14 to 17, 1896, and was attended 'by
its way, but it may be some time before the delegates appointed by the governments of debt to the Royal Society will be extinguished. Canada, Cape Colony, Denmark, France, The financial support given by the different
1 Report presented at the annual general meet- countries is shown in the following list. New ing of the Royal Society of New South Wales, Zealand has not become a contracting body: May 3, 1905.
Austria, £165; Canada, £119; Cape Colony,
£109; Denmark, £102; Egypt, £17; Finland, issue was 43,447, and 'the total number of £45; France, £754; Germany, £901; Greece, entries in that issue was 149,768. The num£34; Ilolland, £133; Hungary, £68; India and bers of books and papers indexed in the volCeylon, £471; Italy, £459; Japan, £255; Mexico, umes of the second annual issue are as fol£85; New South Wales, £34; New Zealand, lows: A, mathematics, 1,813; B, mechanics, £17; Norway, £85; Nova Scotia, £17; Orange 841; C, physics, 2,433; D, chemistry, 5,632; River Colony, £17; Poland, £17; Portugal, £17; E, astronomy, 1,223; F, meteorology, 1,988; G, Queensland, £34; Russia, £512; South Aus- mineralogy, 1,307; H, geology, 1,702; J, geogtralia, £34; Sweden, £85; Switzerland, £119; raphy, 2,022; K, paleontology, 638; L, genUnited Kingdom, £765; United States, £1,251; eral biology, 689; M, botany, 6,339; N, Victoria, £17; Western Australia, £17. Total, zoology, 7,131; 0, anatomy, 1,424; P, anthro£6,755.
pology, 1,861; Q, physiology, 9,671; R, bac
teriology, 3,132. The total number of entries Germany ............ 146,552
in the author catalogue of the second annual France .............. 46,702
issue is, therefore, 49,876, an increase of United Kingdom 43,484
6,429, or about 15 per cent. more than the United States ........ 37,688
number in the first annual issue. The total Russia
21,071 Italy 13,473
number of pages in the first annual issue is Holland ....
8,387. Austria 6,379
The foregoing table shows the number of Poland .......
slips received and the instalments in which India and Ceylon..... 2,231
they were supplied to the central bureau. Japan ......... 2,208
It was originally intended that the catalogue Switzerland .... 1,932
should not only contain the titles of papers, Hungary
but that their subject matter should be fully Denmark
indexed also; financial considerations have, Sweden
however, led to the number of subject entries Victoria .....
being at present limited in number. The title Norway
1,303 New South Wales 1,016
slips received at the central bureau very often Finland
showed that the papers were insufficiently inSouth Africa ...... 645
dexed, especially in the lists of new species in Belgium
botany, zoology and chemistry; in many cases Canada
the central bureau has made good these deficiNew Zealand ........ 327
encies. The executive committee urge that South Australia ......
efforts should be made in all countries to Western Australia ... 16
supply fuller information as to the contents 343,503
of papers; if this were done the catalogue
would be much more complete and the cost It has been suggested that special efforts would be much decreased, and all journals are should be made by the regional bureaus to urged to index each paper and attach the bring the catalogue under the notice of scien- · registration numbers at the time of publicatific workers, and to secure an increase in the tion. number of subscribers. The whole of the At the meeting of the international council first and second issues of the “International held at the Royal Society's House, London, Catalogue of Scientific Literature' have been Vay 23 and 24, 1904, it was resolved, in conpublished with the exception of the volumes sequence of the success achieved by the ‘Inon botany and zoology; the third annual issue ternational Catalogue of Scientific Literais in preparation and several of them are ture, and of its great importance to scientific already in the press. The number of entries workers, to recommend that its publication be in the author catalogue of the first annual continued. The agreement with the contract
I wo coor Bow