166 



KNOWLEDGE. 



[July 1, 1895. 



reduction of the amount of typhoid in the army, the present 

 number of cases being considerably less than half of that 

 which existed at the beginning of the experiment, but also 

 examining the figures of some thirty of the principal 

 garrisons which had in earlier years been the most aft'ected 

 by typhoid fever. The result of this examination is to 

 show in detail the accuracy of the general statement made 

 by M. de Freyciuet in 1892 ; the conclusions being in 

 many cases checked by the re-appearance of the disease 

 immediately, through any cause, the use of the filters was 

 discontinued. General Zurlinden, in fact, shows that such 

 cases of typhoid as occurred, and must in an army of 

 half a million of men be always inevitable, are either 

 contracted externally at bars, inns, and the Uke, or have 

 resulted from the accidental contamination of some water 

 supply, previously regarded as sufficiently pure to be used 

 without Pasteur filtration. 



Similar results have been worked out in special cases by 

 independent medical observers ; and the Pasteur filter may 

 accordingly be taken as a rehable and convenient standard 

 for the efficiency which is necessary to prevent water-borne 

 disease. Any filter which, tested simultaneously and under 

 identical conditions with micro-organisms furnished ex- 

 perimentally with artificial assistance to growth exceeding 

 that which will occur in ordinary water, oflers for a suffi- 

 cient time the same resistance as does the Pasteur, may 

 at once be taken to give the same efficiency of filtration. 

 Any filter which does not must be condemned, unless 

 evidence be forthcoming to show that the efficiency of the 

 Pasteur filter exceeds that which is necessary for the pre- 

 vention of disease. An unfortunate instance of the results 

 which are liable to occur through the use of inadequate 

 filters came out recently in the House of Commons, where 

 the Minister representing the War Office stated that an 

 epidemic of cholera which occurred last year at Liu-know 

 had been now traced by a special committee, appointed 

 by the Government of India, to the pollution of the barrack- 

 room filter. This epidemic had been confined to the troops 

 of the East Lancashire regiment, which used this particular 

 filter. The strength of the regiment at the time was six 

 hundred, out of whom one hundred and forty were attacked 

 and ninety — or nearly one man out of every six in the 

 regiment — died. 



Some iXtmxt patents. 



Joseph Thuclier Clarke, Boston, Mass., U.S.A. Impvoveuients in 

 or relating to apparatus for the exposure, separation, and storing of a 

 paek or series of photographic films. This iuTention consists in an 

 arrdngement bv means of which a paek of sensitized films, or like 

 llexible sheets, mar be exposed in connection with an ordinary photo- 

 graphic camera, and may thereafter be transferred seriatiin to a 

 light-tight receptacle, where they are stored in another pack or scries. 

 The edges of the films are notched, as shown in Fig. 1. In making 



N 



9 (shown in Fig. 2) is a push plate, which 



\f^ 



the films are supported, 

 is pierced by 

 two diagonal 

 slots II I, 10, 

 in which play 

 two pins 11, 

 11, projecting 

 from the cross- 

 bar 8. A lobe 

 of the push 

 plate 9 pro- 

 jects through 

 a slot 12 in the 

 casing, and is 

 fitted with a 

 handle 13. By 

 sliding the 

 handle 13 to 



and fro in the slot, the film-changing mechanism may be operated 

 from the outside of the case. Tlie films are thereby released alter- 

 nately, and allon-ed to fall from the magazine into the receiver. (The 

 Frena Film Holder. R. iV J. Beck, L >ndon ) 



So. 2.566. Bated 6t/i Februari/, 1893. Firefiaures. 



\^^^^'^^^ 



1,'harles Scott Galloway, Glasgow. 



U]) the films into a pack, an alternate sequence is maintained as regards 

 the position of these notches. The front of the magazine is provided 

 along its sides with two series of projecting teeth. Upon these teeth 



Improvements in steam boilers. 

 This is a combination 

 steam boiler. In the 

 figure, which is a trans- 

 verse sectional elevation, 

 A and B are two fur- 

 naces formed to the re- 

 quired shape to fit into 

 the shells or water- 

 jackets C and D. The 

 furnaces are not concen- 

 tric with the shells or 

 water-jackets, but are 

 placed below the centre, 

 making the space be- 

 tween the top of the fur- 

 nace and the shell or 

 water-jacket the mini- 

 mum required for a man 

 to go inside and expand 

 the tubes. G G are cir- 

 culating water tubes ex- 

 ternally heated. F is tlie 

 steam and water drum. 

 The products of com- 

 bustion travel through 

 the furnace tubes A B, 

 then pass up the back, 



coming forward among the tubes G, and upwards to the flue. J J are 



walls of non-conducting material. 



No. 19,913. Dated 19tt October, 1894. Accepted 24t/i Maj/, 



189-5. Two fiqures. 



THE FACE OF THE SKY FOR JULY. 



By Herbert Sadler, F.K.A.S. 



BOTH sunspots and faculte show but little decrease 

 in either number or magnitude. Conveniently 

 observable minima of Algol occur at llh. 48m. 

 P.M. on the 3rd, at 8h. 37m. p.m. on the 6th, and 

 at lOh. 19m. p.m. on the 26th. 

 Mercury is invisible during the first half of the month, 

 being in inferior conjunction with the Sun on the 1st. 

 After that he becomes a morning star, rising on the 16th 

 at 2h. 57m. .\.m., or Ih. 6m. before the Sun, with a 

 northern declination of 19° 48', and an apparent diameter 

 of 9-0 ', about xoths of the disc being illuminated. On the 

 21st he rises at 2h. 45m. a.m., or Ih. 24m. before the Sun, 

 with a northern declination of 20° 45 , and an apparent 

 diameter of 7f ", tVcj^I^s of the disc being illuminated. He 

 is at his greatest western elongation (19^ 55') on the 23rd. 

 On the 26th he rises at 2h. 41m. a.m., or Ih. 34m. before 

 the Sun, with a northern declination of 21*^ 28', and an 

 apparent diameter of 6j", nearly half the disc being 

 illuminated. On the 31st he rises at 2h. 51m. a.m., or Ih. 



