Ana. 7, 1885.] 



KNOV/LEDGE ♦ 



#ur 5nbnitoi£f' Column. 



PUOTOGEAPHIC CAME1!A. 



-by Mr, 



[Patent No. 4,528. 1885.]— We have here an invent 

 '. F. (Stanley, of Railway-approach, London-bridge— .^ „^,^l^ ^ 

 iparate focussing-cloth is dispensed with. In this camera, by the. 

 idition of a light, conical silk bag placed horizontally behind the 

 cussing screen, the ordinary loose focnssing-cloth is dispensed 

 ith The same conical bag carries at its apex a magnifier which 

 isw era as a focussing glass, and the whole appar-itus becomes 

 when the focussnio glass and cloth are separate parts 

 \t the same time the he-id of the 

 not stifli 



light( 



3ubjec 



D the r 



its blowing about 

 nil loss in windy weather 

 quite protect the camera from 

 lit a second loose feilk cover 

 iws over the bellows and open 

 rts This patented apparatus 



_ 1 be adapted to anv camera 



"''^'"- — iaT " An important feature is that the 



f/¥ \ operatoi is able to look about him 



Wra " at tht time of focussing to secure 



the best view and avoid any 

 1 that maj appear from moving objects Iho conual 

 Dag IS made to stand out at the focus of the glass, when required, 

 by pressing it upon two studs. 





METALLIC VAPOURS. 



[Patent No. 7,731. 1884.]— It is well known both to agricul- 

 turists and metallurgists that proximity to smelting-works is not 

 conducive to the production of large crops or to the health of 

 cattle pastured on such land ; in fact, the records of our Law 

 Courts show us that manufacturers are continually having to Sght 

 actions brought by neighbouring landowners for damage sustained 

 by their property caused by the deposition of acid and metallic 

 vapours from their chimneys. 



Many plans have been introduced from time to time in order to 

 prevent the emission of metallic vapours into the atmosphere. 

 Some few of these are chemical, but most mechanical in their 

 action. The plan patented by Mr. Ernest II. Cook, B Sc, of 

 Bristol, is very simple, and at the same time proposes to 

 recover some at least of the valuable metals, as well as sulphur, 

 which are now allowed to vitiate the surrounding air. The raw 

 material which is used in the process is the waste product from the 

 alkali works. This material, large quantities of which accumulate 

 near chemical works of this description, is at present of practically 

 no value— in fact, is a source of annoyance, and any use for it 

 would be a benefit not only to the alkali-maker himself, but also to 

 the dwellers in the vicinity. When steara or steam and air is blown 

 through this waste, a large quantity of the sulphuretted hydrogen 

 or of the alkaline sulphides, which it contains, are removed and 

 carried along with the steam. If this steam thus charged be 

 brought into contact with sulphurous anhydride, a chemical de- 

 composition ensues, resulting in the deposition of sulphur. Any 

 metallic compounds are likewise decomposed, and the sul- 

 phides deposited. The application of these facts to practice 

 is exceedingly simple. In almost all smelting - works the 

 gases from the furnaces are made to pass through a series of 

 long flues and chambers prior to their exit from the slack. In 

 these flues the gases are cooled, and a large portion of the sub- 

 stances deposited. Mr. Cook proposes to pass into these fines, 

 chambers, and passages, at various intervals, the steam charged 

 with the sulphuretted hydrogen obtained as before mentioned. 

 Immediate chemical action occurs, resulting in the precipitation of 

 large quantities of sulphur. The metallic substances present 

 combine with the sulphur of the sulphuretted hydrogen, and are 

 deposited as sulphides. The formation of the solid sulphur by the 

 union of the two gases aids the deposition of the metallic com- 

 pounds by mechanically enclosing them, and the result is that no 

 metallic vapours reach the stack to bo given off into the air. 



Thus this process, in addition to affording a protection to the 

 smelter from the, in many cases justifiable, complaints of his neigh- 

 bours, furnishes him with a means of regaining as a marketable 

 article a substance which is now allowed to escape. When it is 

 mentioned that for every ton of lead made from galena there is 

 produced more than six hundredweight of sulphur dioxide, the 

 importance of recovering the sulphur becomes evident. 



is of very general application, as sulphur dioxide is an 

 "it product in all motallurgical works. 



"Let knowledge grow from more to more."— Alfred Texnyson. 



Only a ■fmall j))o;io)(ioii of Tetters rerc^>cd can possilly he inserted. 

 Co}ie pondent^mvit not le offtnded thetefore, should their letters 



il It fn the opinions of correspondents, 

 ml Fubt Office Orders should be made 



V Sons 



THE RLDDl ECLIPSED MOON. 

 ly I be perm 



for the " ruddy eclipsed n. _ - 



the merit of being a common-sense one. In the absence of n^^-^^- 

 light, when the atmosphere is clear and transparent, and the stars 

 shine out in full effulgence, we become sensible that a large amount 

 of light from that source passes through our atmosphere by the 

 distinctness with which distant objects are seen in considerable 

 detail. The moon, like the earth, is surrounded by the starlit 

 heavens, and should reflect from her surface sufficient light to 

 make her non-sunlit disc more or less visible to us in times of 

 total eclipse, as circumstances are more or less favourable. The 

 pale or ruddy colour must depend on conditions of our atmosphere 

 as to the amount of moisture diffused in the higher regions. If 

 the sun rises in fog it assumes a ruddy colour, which becomes 

 lessened as he rises towards the zenith, even though the fog 

 remains as dense as at his rising. According to this theory, the 

 eclipsed moon should be more ruddy at times when i' 

 setting in eclipse, and when a( 

 solstice of our atmosphere. ±ir..>i». u. ^^i-.^^.. 



[The " large amount of light" which Mr. Madge appears to sup- 

 pose reaches us from the stars has no existence, save in his own 

 imagination. Taking a Centauri as his standard star of the 1st 

 magnitude, Sir John Uerschel determined that a cluster of 27,408 

 such stars would only give the light of the full moon. There are 

 never more than 1,000 stars visible at one time on the darkest 

 night, and of these, /our, perhaps, will be of the first magnitude. 

 Further, bearing in mind that it would take 2i stars of the 2nd 

 magnitude to make one of the 1st; 6 of the 3rd, 16 of the 4th, 40 

 of the 5th, and 100 of the Gth magnitude to emit the light of a 

 single star of the Ist magnitude, it will easily be seen how wild is 

 the notion that we are indebted to the stars for any sensible 

 addition to the lightness of our nights. Whithersoever we derive 

 it, it is not from them.— Ed.] 



r the meridian in the winter 



THE PAST OP THE MOON. 

 [ISkS]— I think there is some value in Mr. Mackie's contention 

 that there might have been men in the moon, but that they had 

 not time to develope as wo have done (letter 1812)- Again, they 

 might have been pygmies. Si ill, when we look back, and see that 

 there must have been human works thousands of years before the 

 Pyramids— such as riey liury in Oloucestcrshire,' a quadrangular 

 earthwork which from tlio moon would bo a fine object with a not 

 very high power— iiiul wlion wo consider that the earth is no less 

 habitable, no cool,!- th:ni in tlioso [last ivons— nay, much hotter 

 than i.i s-rn. II -I I ,1^ piohable enough that the moon's inhabited 

 days il' i'^ 1 II -lasted long enough for the lunarians to 





p of river-beds in the n 





I 



