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successfully performed under favourable conditions; but in effect be admits tbat, whatever may be tliu conditions, tbe success or failure of tbo experiment is dependent upon the merest chance, for be adopts nearly the same argument as was used by Mr. George Shepherd, an English weather forecaster, to account for the fact that no dependence whatever could be placed upon bis forecasts. "Bat," says Mr. Le Maout, " if it does not rain upon us when we fire the cannon, or when we I in■:. it may rain somewhere else, especially when tin sky is charged with rain-cloud within I i'ected by the
sonorous body. Thus, not only may rain fall in the neighbouring village, but even at immense distances, since in the great disturbances of the aerial mass by the formidable I artillery at the
siege of Sebastopol it often rained her.' (iiiBiittauy) although not a drop fell in the Crimea." Prom this it would appear tuat our great pharmacist is not so uracil in want of correct premises ad of ability to deft} with them; but it is precisely this latter want that gives us the aöra.sing absurdities be has treated us to. Often, hecirathines, the firing of the cannon ami the feo'iuid of the bells clear the cloudy sky, and send the threatened storm afar.
Similar effects were observed, not only during the Crimean war, but during that of Italy, and of the Austriaus and Prussians; and he observes that storms were more frequent than usual darillg those events. In confirmation of bis views he reminds old military officers that at the siege of Antwerp the besieged were constantly under torrents of rain, and up to the knees in mud, but that as soon as the citadel was taken the rain ceased, and the weather became tine. They will remember, too, the memorable storm of bail, rain, and wind which occurred before four and five o'clock in the evening on the battle-field of Solferino, which alone put an end to the fury of the combatants, ami saved the remnants of the Austrian army. In that case tbe physical force was accumulated by the powerful means used, which had the effect of concentrating the hurricane upon the battle-field itself, the battle acting incessantly like a suction pump. He accounts for the storm at Puebla and the nonsuccess of French arms in Mexico in a similar manner, and it seems that even England may well be thankful that M. Lo Maout's doctrine was not accepted half a century earlier. The success of England in some of her greatest conflicts with foreign nations has frequently been attributed to her knowledge of war and water ; and lin another sense it is true) Mr. Le Maout attributes the loss of Waterloo by the French to the want of that knowledge. If, he observes, Napoleon I. had known this condensing power of cannon, which, by tbe way, he could better than any one else have observed upon so many fields of battle, he would not have undertaken, upon June 10th and 17th (the eve of Waterloo and day previous), the battle of Ligny, and the engagement with the rearguard of Gcnappes, during which a storm occurred, commencing about three o'clock in the afternoon, and continuing for twelve consecutive hours to pour down torrents of water, which converted the ground into a perfect marsh, aliko impracticable to man anil beast. It was tbe twenty -four rounds fired on ibe retreating English columns that, in Mr. Le Maout's opinion, brought down the rain, and prevented the movement of the French troops until the following day, by which time the Prussians had arrived; hence the loss to the French of the battle of Waterloo.
It is difficult to determine whether Mr. Le Maout is the moro worthy of admiration as a philosopher or as an historian; but as we are not called upon to give a decision, the question may consequently be left to our readers. We will content ourselves with explaining how the great discovery is to be turned to practical use, by recording a statement of the conditions which he regards as most favourable to success. The instructions агз given for St. Brieuc, so that experimenters will have to make the necessary corrections for locality if applied elsewhere. Make the experiment with the wind blowing from the south-west and earning heavy rain-clouds, anil choose a day when the" barometrical pressure averages less than 76 centimètres. Commence in the morning, before the misty bank formed on tbe surface of the English Channel is dispersed by the rays of the sun. The lower the temperature the better. Proceed by simultaneous explosions from one or several batteries every quarter of an hour. Upon this day all military target practice should be suspended; and if the experiment be made upon the day of a religious feast, when the bells ore rung, the probability of success will be all the greater. If the experiment succeed, and it be judged that sufficient rain has fallen, transport the condensation cannons from Cherbourg to Brest, and fire again to stop the current of vapours coming from the ocean by condensing them in their passage. Thus, to have rain, fire at Cherbourg on the rainy winds of the south-west ; to have dry weather, fire at Brest on the easterly winds which reach there after having traversed Central Europe, and been deprived of their vapour of water by the numerous bells in Christian churches and the noise of military exercises which they have met with on their way. There is, in Mr. Le Maout's
opinion, reason to believe that if the condensation cannons, which act like a suction pump, were kept in energetic motion on the English Channel, the vapour of water would flow there and fall as ram, not only from the west, but from the Mediterranean and the Northern ocean. Is this to be accepted as а result of enparior technical education on the Continent?—E. D. H., in the Scientific Review,
HINTS ON WATERING PLANTS.
AS I have a good deal to do in various ways with amateur gardeners, I have frequently opportunities of noticing their shortcomings in a variety of particulars. In ninety-nine cases outjof a hundred almost, lathes and gentlemen who are excessively fond of flowers, have a little plot of garden, perhaps a greenhouse and a frame or t .-o, and bestow a good deal of time, money, and pains, do not realize the results they think they have a right to expect as the reward of their application. I think we may plaee some portion of the failure to the account of the want of tact, which Johnson defines to be *'expertness and skill in the management of any affair; ready tftleut.'' Let something more go down to the lack of untiring vigilance, indomitable application. One single neglect of some particular item in the routine of management will sometimes render nugatory a whole year's attention. If the clock discontinues its ticking, notwithstanding the monotony of the process, family and business arrangements aro thrown into confusion. Then, again, observation quite justifies me in saying that, in very manteases, sour mould, injudicious mixture of soil, bad potting, and imperfect drainage, completely block up the way to success. But the one great hindrance, on which I purpose for a moment or two to dwell, is injudicious watering. To be plain, there is no rule that can be laid down for watering plants in pots. Some persons ask, "Should not plants in pots be watered every day?" The answer is, "Every collection of plants in pots should be looked over every day, and tliose that are dry should be watered promptly and sufficiently." Let me explain wfiat 1 mean by "sufficiently." When a plant is potted, there is a space between the surface of the mould in the pot and the margin of the pot; this is to hold the water necessary for the plant growing in the pot; if the space is pretty deep—say jin., or an incfi—this space quite filled np with water will generally be enough for one dose. H the space is shallower, and the 'plant is very dry, it may be filled щ> two or three times, as the case may be, until the ball is thoroughly moistened. If the ball has got so dry that the earth has shrunk away from the sides of the pot, and the water when poured in runs away between the ball and the pot without penetrating among the roots, after the first dose has been given, draw the finger all round the opening on the top of the soil. This operation, simple as it is, wall detach mould enough to till up the gap, and the water which is afterwards given will, instead of running away uselessly, permeate the entire mass of soil in the pot. And let it be remembered that this "sufficient" watering applies to winter as well as summer treatment: it is a mistake to give plants in pots that are dry only water enough to moisten the surface of the soil. Subjects that in the summer require copious supplies of water every day, in the winter, perhaps, will not want it more than once a week; but when they do have it, give them enough. I would also persuade amateur gardeners to adopt feeders, or saucers, or pans, or whatever may be the name by \yhich they are locally designated; these will be found to be of incalculable advantage to many plants: not the glazed pans, but those of the same material and finish as the common garden pot. First of all, the water which has passed through a pot of soil that has become dry will be retained by the saucer, and will be absorbed by degrees, according to the necessities of the plant. Then, again, the pan itself absorbs а considerable quantity of the water, and furnishes a moist, cool bottom for the plant to stand upoti, most grateful to plants of all lands, and analogous to standing on a bed of ashes or sand out of doors, where they are always found to enjoy themselves.
Further, there arc numbers of plants that positively delight to stand in water. Fuchsias, all through the growing and flowering season, begonias, arums, callas, ixias, many ferns, and other things, will amply repay by their luxuriant vigour the indulgence of being permitted to stand in a pan of water.
Again, it will be a great relief to many an anxious cultivator who leaves his home in the morning, and as he takes a last look at his potted plants, to feel sure that, by leaving them a supply of water within their own reach, their necessities will be met through the length, it may be. of a long, bright, parching summer's day, to find at his return home, after the toils of business, that his plants are not only not perishing from drought, but are, perhaps, considerably improved in vigour and beamy. Only once more let me say that, in using pans, adapt them to the size of the pots—that is, let 48-size X'ans be used for 48-size pots, and the same with other sizes, as it will be found that,
if they are too large, they contain icotf sitsr than can be absorbed by the plant while it u srat and, if too small, will not contain enough.
I am afraid your readers will think I give then credit for very little knowledge, but it а Ьесаач I know that a very large proportion »re при". cultivators, that I can speak so plainly loi ил adrice of beginners. Bat just another moment, while I place two or three guards around tb, practice 1 have been advocating. Let eveuyftmg placed ill pans be well potted, sufficientlydrahi'-î and filled with roots, and for innumerable snbk-rts. such as roses in pots, vines in pots, orckard-trf~ fuchsias, and strong-frrôwîinjaiid free-rootingtliiii.'. generally, this ВШ be found a most satisfact*Tj provision.—By William Cunrr, in the FU/n' World.
THE EVAPORATION METEE FOB
TRLVLS made at different times oïflnc evapon.Uve effect of different constrnertou» oí boíu and different binds of fuel have ehejw« considerable variations in the relative amounts of steam produced. The canse of these variations may btlceir.' for—first, in the construction of the boiler and ii setting; second, til the Quality of the fuel ; tan' in the qualification of the fireman.
The fuel for steam boiler» tonus such a 'of item in the expense account that it is cerutisr*: the greatest importance to owners of boite ■ make themselves familLur with the propunii; which the production of steam stands to the »птозу of coal used, and to reduce the latter, if possjhk
Official trials of the evaporative effect of Ê ferent construction of boilers, and different qnalafc of coal, girt- important i nformaUon: hot aitaiiirr ness and skill of the fireman, a very imjwmi: factor in tbe saving of fuel, «is»! be testai Ь single trials, but only Ijy continual ntckkf. and increased only by introducing а ^rsiem Ы mu'cs which depends upon tl ae amoaul oí соя/ s»i>¿ The important results obtained bt the latter erbfau is clearly proven by the fact that»bee its ¡лЫвгtion in the case of locomotives, ai «ïêrage a^iig of fuel of over ten per cent, has bita ottaitel thereby.
On railroads the record of «ach ¡oeumotiv в made up from notes of the freight earned, аиН'ю distance travelled. The differences in tie grades oi the road are regulated by coefficients.
With boilers for stationary purposes, such a system of control cannot be employed, for the kind of effect is generally variable, and a ¡roe measure for them does not exist. Moreover, tie oserai effect is dependent not only open the engineer ami fireman, but also on erery irerkniau operating J machine. A more direct mte of tbe efficiency of the fireman is the exact measure of the steam produced. At different times attempts nave been made to del emane this point, by passing the water fed to the 1юйег. through a meter. Most of these meters have been condemned ou aecoont of their want of acciiracv and durability. All watemcters. however, are not adapted to steam builers, as the? do not note the temperature oí the it«à«ato. The chief point is not to ascertain the iraoiitity oí the water evaporated, but to establish the amount of heat applied to the boiler bv the coutatum of the fuel. The ratio of the quantity of beat made useful to the amount contained in tbe iad lorms the basis for estimating the efficiency oi the Ыеmau, and the perfection of the boiler constructmu The feed-water offers the means for measarin!; Ш effective quantity of the heat, but it is not sonta: to measure its quantitv alone—the température il which it enters the boiler must also be carefc/ considered.
In trials of short dnration. the temperature л» feed water can be noted and eutered in the eil» tion, but iu practice this can not be done wlie* object iu view is not one short trial, bot thai»tinuous observation winch is necessary for a Beplete control of the fireman.
The evaporation meter, which v,c hereP«*?1; answers every demand. It Ls not damaged by be. water, the measurements are correct, and it « cords the temperature of the water entering Ь boiler, so that on its index-dinl the quantity of tes. made effective may be read off in heat units. I will be seen on examining the annexed cot, that ¡» water which enters the apparatus rises npiraf^ through the channel B, and falls on the e"**¿ over which it flows slowly downwards. By tba means the feed-water conies in direct contact ИВ the steam of the boiler, which bas free access to.i>interior of tbo apparatus through the pipe • The feed-water is thereby heated to the b*' perature of the steam, and falls with the «» densing water into the box E. It then enNo through the passage F, the «Irani G, which w*»TM six helix-shaped compartments. The dram I*d(>^J on one side, except the central opening. tniw-' wliich enters the passage F, and is open l>n ' , other side. The lower part of the dram is innw^ in the semi-cylindrical basin H, the npyvr eofê" „' of which is below the lower edge of the pensas0 r The entering feed-water fill« the compartments, and thereby causes the drnm to revolve. The number of the revolntions of the drnm is exactly proportionate to the quantity of water passing through. To reduce the friction in the journals as much as possible, the shaft of the ilruin rests on its two units, at О and N. on friction rollers. The water passing out at the open end of the drum falls over the edge J, into the steam boiler. The revolutions of the drum are transmitted to the shaft L, arranged VÜb conical packing, passing through cover K, and operating a counting apparatus, placed outside the «team-room. A small air-cock on top of the upper cover serves to permit the escape of the atmospheric air brought over by the feed-water.
As one of the merits of this apparatus we may mention that it is constructed without any packing. Moreover, the drnm effects the measuring with »such accuracy that it excels in this respect anyother water meter, and this accuracy is not influenced in the least by impurities carried along by the feed water. The formation of scale will disturb the action of tins apparatus much less than any other known water meter, there being, aa already stated, no packing whatever, and all the cross sections being very large. The registering apparatus is entirely removed from the influence of water aud steam. The basin with the drum, as well as the cascade, can easily be taken out and cleaned from scale oitlmr by the hammer or by treating it with ililuted murin tic acid.
Another great disadvantage of other water meters is that in the case of interruption in their functions the feed of the boiler is entirely stopped; .stich a case cannot happen with the evaporation meter described above.—¡fingier"» Polyteçhnitchea Jnurna¡.
CONFERENCE OF MECHANICAL ENGINEERS.
THE annual conference of the mechanical engineers of England commenced at Nottingham on Tuesday. There was a numerous attendance, including all the principal engineers of this country. The chair was occupied by Mr. Hnwksley, of London. The following is а list of papers to be read during the rouferenee:—" On Self-Acting Machinery for Printing Hosiery by Power/' by Mr. A. Paget, of Loughborough; •' On the Mode of Working and the Mechanical Appliances in the Midland Coal-fiold," bv Mr. George Fowler, of Nottingham; "On a Steam Road Roller," by Mr. W. F. Batho, of Birmingham, and Mr. T. Aveling. of Rochester; "On the Mechanical Ventilation of the Liverpool Passenger Tunnel on the London and North-Western Railwav," by the President; "On the Conclusions derived from the Experience ot rec« - .-. .... ■ :■ . ■ Uxpln-dons," by Mr. E. B. Muten, of! :and "Description
ufa Self-Acting Safo! rig "falve
for Steam Bofl r. G. L>. Hughes, Notting
ham. On Wednesday, August 3, the best means of preventing boiler explosions was discussed. Mr. E. Marten, Stourbridge, stated that 210 explosions had occurred in England during the last four year«, resulting in 816 being killed and 150 wonnded. Eightyfour were Cornish or Lancashire boilers, 53 plain cylinder, 12 marine, 10 locomotive, 11 agricultural, H upright furnace; 6 crane, (5 rag steamers, 1-1 domestic, and 15 miscellaneous. The causes were :— Cornish and Lancashire, ill-formed tubes, weak combustion chambers, domes, ate.; plain cylinders, llat ends, and frequent repairs, resulting in seams and rips; marines, weak flues, Ac.; and locomotives, want of stays. It was stated that the only preventive was constant and careful examination on the part of the owner. Government inspection was not recommended, as it would tend to relieve the owner of all responsibility. Mr. D. Hughes, Nottingham, brought forward a plan for the construction of a self-acting safety and lire-extinguís hing valve. It was generally admired, the object being to secure boilers from the danger »irising from pressure and want of water.
for his interesting essay, and the following questions* forwarded by members, were proposed for consideration at the next meeting.
I. Give an explanation of the action of the ejector condenser, with a sketch.
II. Information required on Clayton's patent scraper, as used with the fuel economizer.
III. Any member's experience of the Birmingham patent safe and suro sectional wronght-iron boiler; how it is for steam-room, foa comparative consumption of coal, and any practical information thereon.
LETTERS TO THE EDITOR.
ENGLISH MECHANICS' SCIENTIFIC AND
The fourth monthly meeting of this society was held at the society's room, Mechanics' Institute, Manchester, on the 3rd inst., when a paper was read on :' The Ancient and Modern Means of Communication," by Mr. A. Tolhausen.
The speaker said that the double meaning of the word communication as being, firstly, the making known of certain things, and secondly, the means of passing from place to place, would necessarily lead him to two distinct considerations of tho subject. After giving a brief outline of tho difforout stages of written and spoken language, he compared the aucient mode of giving both diffusion and perpetuity to speech with the modern instructors of mankind "the Pen and the Press," and then proceeded to tho postal and telegraphic systems as further means of communication without change of abode. The second part of the essay followed under tho headings of inland and maritime conveyance, when tho inland moans of communication were considered, snch as roads, coaches, rivers, canals, and the railroads, together with the maritime postal service. After tho discussion the thanks of tho members were awarded to Mr. Tolkauscn
of Mr. Brandon on my head, I am strongly tempted (with your permission) to say a few words to a couple of gentlemen who have honoured mo by criticising some of my more recent dicta in your columns.
Aud firstly, Mr. Usborne (1401, p. 458, is indeed " a bold man, " "taking up tho cudgels" as he does, not against the present writer—who is, goodness knows, a sufficiently humble person—but against a most perfectly ascertained and well-known law of motion. It is as though aman should take credit for pluck in describing me as a bad aritheiuetician (which he might or might not have a distinct right to do), but who, all the while, was merely proclaiming that two ami two Ьу no meaus mude four. Is it possible that Mr. I , has never heard of the «ouipositiou of for
An express train on the Great Western RaUwa at the rate of 60 miles an hour; tbatts, 1,760 yards и minute, or 29 ¿ yards iu a second. Now, does Mr. usborne seriously believe that it' a missile ware projected vertically Upwards from, th« floor of a closed carriage in a train moving at this rate, to a sufficient height to retain it in the air for one seond, that it would fall 29j yards behind its initial point of departure V or, that if a man fell off tho main-top-gallant mast of a ship sailing rapidly aud smoothly along the Saez Canal that he would "not fall accurately at the foot of the mast, because the vessel would have moved onward between the timo of his starting aud that of his. reaching tho deck?
I hope that your correspondent will not conceive that I am guilty of any want of what he is so flattering as to term my "invariable courtesy" if I counsel him to go to the next circus that comes into his part of the world, and notice carefully how anything that ono of the riders projects perpendicularly returns to his hand, and does not (as Mr. TJ. seems to think should he the caso) fall to the rear of his horse; or how the said rider, when he wishes to jump over a flag or through a hoop as be careers round the ring, does not spring forward, (ho would infallibly ко over his horse's ears if he did), but straight up. Having taken this easy practical lesson then, I would beg my critic to spend a shilling or cighteeu-pence in any rudimentary treatise on mechanics (such as Tomlinsuu in " We ale's Series"), aud read up the very elementary dynamics needful for its apprehension. Or he may turn to Mr. Keruan's paper on " Science for the Young," on pp. 318 and 837 of your current volume, for a statical demonstration of the composition of force, and so obtain an idea of how the proper motion of the engine which projects any given particle, never deserti that particle at any instant of its flight, but is always compounded with that of projection. If the earth were moving at the equator with a velocity of rotation of 10,000 miles instead of 1,000 miles an' hour, aud it were possible to shoot a ball absolutely perpendicularly from a gun (or rather a howitzer or bomb) iu vacuo to the height of two miles, it would merely fall back into the muzzle again. After which it is scarcely worth while to remark, that Mr. Gould (p. 878 speaks, a-* I assume, of firing, what artillerists call point-blank from west to east, or east to west, aud not perpendicularly at all; nor that "the theory of projectiles " м a most exceedingly complicated subject, albeit from very different causes, to those assumed by Mr. Usborne.
I have very little to say to Mr. Firth, p. 450. I will not be answerable for press errors, which I have ш» opportunity of correcting, and therefore he must tight out his 4h, 32m. and 8h. 3üm. with your compositor. I, however, plead guilty to а Харви* calami in writing 2Sht for 27th.
I have not discontinued—at all events permanently— giving " the times of rising aud setting of ноше of the planets," as Mr. F. may seo in the very mBaber in which his own Utter appears.
His third paragraph seems, to my obtuee perception, to be a remarkably successful imitation of utter nonsense. Suppose that I say that a certain superb instrument is situated iu latitude 51° 28' ätt N-, and longitude Oh. Om. Us., and that it is сопицшпИу in the transit circle room of the Royal Observatory at Greenwich. I wonder whether "it must Ъе acknowledged by all" that "the inference or deduction is illogical?"
I havo sir, a favour to ask you, and it Í3 this: merely let Mr. Firth write your "Astronomical Notes " for September. He is, obviously, bnrningly anxious, to distinguish himself ; aud if he has got it into his head that I derive the very smallest gratification from wliat, after all, is little better than more compilation, the sooner ho dismisses such an idea the better. I undertook these " Notes" originally at tho special request of some brother correspondents in these columns, and have endeavoured to framo them in such » Torrn as should bo useful to the mass of amateur observers who road THE English Mechanic. I should sincerely like those of my brother readers who have employed tho M Notes" to have Mr. Firth' , with his zodiacal signs, Ac, 4c, &c, for comparison. Besides, sir, you might sell another 10,000 copies or so weekly if it were known that Mr. F. "did the Astronomy," At all events, it would be only fair to give him the chance; as it is pretty obvious he will not fail for want of confidence, for that (as was once remarked of some one else) OiYPuriam haud tcnuem.de пенс erUtimat. A Fellow Of The Royal Astronomical Society.
Errata In Astronomical Notes For August.—Line 1, dele comma after ** Greenwich; "line 3, Huu's declina tlon, for lm. 31 "9s. read 1' 81*9"; line 4, " Cancer " should bo Cancri; lino 26, "point" is printed for parti in the second column line 9 from tho end, " something" is put where 1 wrote $outhiiuj; in line 3 from end, dele "then."
[1901 Sir,—I have for some time thought of dropping you a note, and now take up my pen to do so. I must "follow suit" and congratulate you on your very good digestion. Within less than four months you have terminated tho individual career of three publications by absorbing them into yourself. I have had some experience of journalism, but I think I never saw a speedier and completer change for the better than has been exhibited by the English Mechanic. Yon have enlarged your size and improved your type; you give bettor paper and better engravings. You givo much superior information; you appear to have multiplied your correspondents, as you have certainly widened the scope and purpose of the paper. I write this without intending a word of flattery, But what pleases me most is the manner in which yon have classified your contents. Tho information \& not thrown together higgledy-piggledy, as it was a little more than a year ago. "Order is Hoaven's first law," said Pope, and order reigns in the columns of the English Mechanic, say I. Having said so much in praise, I have also a fault or two to find—not во much with our editor as with some of our correspond tub. Take, for instance, Mr. Proctor, for whom I have л profound respect. I sometimes say, "What a pity that so able, and withal so geuorons a man, should be so impatient of other people's shortcomings." One would have thought that his studious fellowship with the heavenly bodies would have imparted to his style of writing more of their calmness, dignity, and repose. Woe betide any unlucky mortal who may be in the wrong, and who may happen to assail Mr. Proctor; he is almost sure to be transfixed with an epithet. And thon, again, the "Harmonious Blacksmith," who takes such liberties with orthography and grammar generally. Сufortunately he does this at our expense, A correspondent some mouths since said that he considered the space of the English Mechanic to bo worth a guinea au inch. The "Harmonious Blacksmith" must look upon it as worth about a guinea a yard. He certainly says good things on a variety of subjects, hut he uses such an extraordinary quantity of words that he deprives tho information he is evidently capable of conveying of three-fourths of its value. The quickest way from one point to another is a straight line. The "Harmonious Blacksmith," instead of going from a point to a point in a straight lino, is sure to walk in a circle, and sometimes he describes two or three circles before he gets to the point he aims at. This may be funny to him, but it is tantalizing to many of us who have very little time to sparo. I wish, Sir, he would have a little consideration for our patience and your space.
I mnst take care or I shall subject myself to a similar reproach, so I will end by hoping that the gentle hints I have dropped may not be thrown away.
ELASTIC BOILER AND TUBE SCRAPER.
 Sin,—The annexed cut illnstrates a new
boiler and tube scraper now being manufactured in
New York by the Miller's Tool Manufacturing Company.
On the iron rod or stem are pinned two conical cast
iron caps. These cap« serve as holders for the four scraperc, which are inserted ь" as to have half-au-ine.h boa ing within each cap. At the hack uf each scraper is a steel spring, that allow« the scrapers not only to be compressed and expanded but also to accommodate their hhape to any nnevenness that may happen to be in the tube. The peculiarity about these scrapers is that the scraping edges are chilled in casting, and then ground on emery wheels to a sharp edge. The point of one edge in each scraper projects past the other, но that the tube gets thoroughly scraped and cleaned throughout its entire internal surface. The thread on the stem .•illows piping to be screwed on to suit any length. The scrapers ■■;ч be made to tit any tube, from If in. tu 4in. diameter, and the cost is about one-half of that generally charged forother scrapers. They are said to be durable, and for the purpose intended give entire satisfaction.
THE ELECTRIC LIGHT FOR PICTURES.
L102] Sir,—There are many things in this world that no " fella " can understand. Among those things I place my strangely erroneous statement that the evolution off light by electricity is unaccompanied by heat. Considering that before the year of grace 18*20 I was familiar with and had repeated Davy's experiment of melting platinum within the luminous region between the two charcoal points, that I, of all "fellas," should have stated such nonsense, resembles mj fellow correspondent's signature, "Pax Dei," in being past all understanding. When I road the falsehood and absurdity I had written, I felt strangely tempted to perform that act which has been said to indicate the utmost possible self-abasement, which act, Mr. Editor, I may, for the benefit of those, if any, who commit mistakes which make them feel as small as I did when I read mine, proceed to describe as the acrobatic feat of kicking your own seat of honour with your own foot. The force of self-abasement can no further go.
The advantages of seeing pictures by a light which hardly differs from that of day iu its capability of shewing their true colours, and the absence of any objectionable chemical products of combustion, yet remain to induce my preference for the electric light over that derived from the burning of carbon.
The Harmonious Blacksmith.
 Sir,—I quite concur in all your correspondent "W. M." says upon this question, and there is no doubt that the country he indicates, Kansas, is a tine field for the industrious emigrant, more especially ut this time, for such as are connected with agriculture or stock-raising. At the same time I would say that Texas has all the, advantages of Kansas with a most productive soil, and finer climate, except immediately contiguous to sea coast, only in some parts of that State. In the north-western parts it is eminently calculated for the growth of wheat; in the western for raising stock, on the vast rolling prairies; while Indian corn, oats, barley, vegetables, und fruit, are и Um raised in great abundance. Agricultural labour is in great demand throughout the State, single men earning from £$ to £â per mouth, with board and lodging. These wages enable a man to eave money, aud at the same time he has an ulmudanceof good food. You can suppose this when beef and mutton are not more than ijd. per Ib., and a bushel of wheat can be had for 8s., while as to butter, eggs, and poultry they are both plentiful and cheap. There is room in Texas for 20,000,000 of people. The Land Laws are very liberal. Land can be either purchased, or rented, at a cheap rate, and if a man goes there without capital he can have the loan of horses, implements, food for cattle, \i\, without paying for same, other than the lender to have half of the crops, stock, &c, raised through the labour of the new comer. Of the eight million head of cattle supposed to be in all the United States, five millions are in Texas. They thrive on the rich uatural grasses all the year round, and only require to be looked after from time to time to see that they are all right. I firmly believe that as this State becomes more generally known a vast tide of emigration will set in thither. It can be reached direct from English ports, and steamers from Liverpool run to Galveston in three weeks or thereabouts, or the emigrant may go to New York, and thence by rail at a cheap rate. I have several correspondents in Texas, all of whom give a highly satisfactory account of the country. In comparison with Canada, which being British territory is therefore urged upon the attention of the public
as a good field for emigration, Texas is far, far superior, and a want of knowledge as to the advantages of the State is one of the chief reasons, why more do not emigrate thither. To the small farmer, or to the large one, Texas affords a certainty with care and industry, r.f realizing speedily an independency, and in many cases large fortunes. More especially will this be the case when the existing railways are extended further in, so as to form junctions with the Union Pacific Line and others, and when the Texas Lines are extended west into New Mexico, which as a silver mining district is vastly richer than any yet discovered in the Western States. Texas having a seaboard, though not with тегу good harbour*, is an important feature in a new country for imports and exports, and the time is not, I believe, far distant when both Galveston, and more especially Salnria, in Matagorda Bay, will have a vast number of ships going forward and back to most parts of the world. From Texas may be imported to this country vast quantities of beef and mutton freak, under an improved plan, and also the same plan as is now carried out with regard to Australian meat and its importation here may be adopted with large profits. I think it is the finest country in the world for English emigrants. I have no pecuniar}* interest in advocating the natural advantages of the State, either directly or indirectly. My only interest is to help in any way I can some of my poor hard-working countrymen here to go to a land of plenty, comfort, and security. W. D. King.
[Our correspondent certainty gives a glowing account ol Texas. Correspondeuts would do well to bear in mind that when they recommend so strongly any particular state or colony or part of a colony to intending emigrants they write under responsibility, aud consequently should be careful in what they say; or, at all events, they should take especial care to weil inform themselves before they write.—Ed. E. M.]
A SUGGESTION.—THE HARVEST, Etc.
 Sir,—I have an uncontrollable passion for questioning. Sometimes such questions lead to pleasant
snrprises and valuable information. During a few days' ramble I have met with one or two incidents which may prove interesting to your readers. Then, 1st—Whilst at Kew Gardens Station my attention was drawn to a system of showing the times of the trains invented by the station-master. It is very simple, and saves many a minute of the porters' time. A board and a few strips of pasteboard are all that one requires. The time of the departure of every train during the day is printed on a slip of cardboard. These aro placed in regular order, and directly a train ha* passed a slip of blank cardboard is placed over tbt slip indicating the time of that train, so that a p senger has only to glance at the table to know the tœt of arrival or departure of any train, and so on. I wish to goodness every station master would adopt this plan, and place the board in a conspicuous part of t b station.
2ndly—I don't believe in the alarmist cry of a bad harvest. As far as I can gather, groin will prodaee an average number of quarters. It is only upon light land that a failure occurs, and I opiue that when the light land produces a good crop the heavy land fails, and vie* nena. A facti know is that here the wheat, beau>. and barley are good—very good.
Lastly, your contributor, Mr. Underbill, would кпоШ with delight to be encumbered with fossils, Ac, as I am. I ask, "Do you meet with any fossils when digging?" "Yes, sir: I will show yon some I Sh\> i "Thank you: I am not much of a geologist ?*' M What is this, sir? *nd this, and this, &c, &c., &c. Yon can take what yon please, sir." "Thank you.'* Such is a specimen of conversation held between your humble servant and those he questions. I declined taking specimens, thinking some one might prove mon' generous to the finder than I should, so they remain for the next wandering "English Mechanician" or geologian.
I have not seen your last issue, and may not see the next or the next. If, therefore, correspondents -will take note of this, and querists content themserves hy waiting, I will make up arrears as soon as I am uear a library, and not so distant as three miles from a postoffice.
С H. w. в.
MOUNTING PLANING MACHINE.
[195! Sir,—Perhaps tho accompanying rough sketch might prove oí service to some of your correspondent* desirous of mounting a planing machine on their lathe at a very small outlay. Should yonr space permit the insertion of tho drawing I should feel much gratified.
Ais a Z-shaped casting of iron, firmly bolted to the side of the lathe-bed by four bolts. To it is firmly bolted a compound slido rest. A gnt hand passes from the smallest pulley of the flywheel over two pulleys fixed to the bed of'the lathe near the cono heodstock; the gut passes along round a disc В having a radial slot, and bolt, which is adjustable, seen also from above. A rod passes from the bolt to the tail of the saddle S, which carries the object to lie planed, between two jaws movable by screws or othor means.
This machine works perfectly with light cuts for casting lOin. x Sin. and adjustable to 5in. in height. The edges of the lathe-bed arc chamfered. The slotted disc was suggested by Munro's planer in South Kensington Museum.
References In Plan Of Saddle.
o. Screw to press removable bar i> against easting. ti. Casting to be planed.
t. Iron bar which can be fitted to varions holes in saddle in the same way as bar с carrying pressure
of barley meal; tho outer husk has been separated from it as much as possible, and it is magnified 200
arrowroot, for which inforior varieties are ofton substituted. On p. 583, Vol. X., of the English Mechanic, I gave a figure of the Tacca arrowroot, referring to the Maranta, which I did not give; having now given it, your readers will be able to compare the two sorts.
We often see in print that the starches are readily distinguished from each other under the microscope; certain kinds may indeed be thus distinguished, but to the " tyro" certain species are a source of infinite confusion. When potato starch is mixed with the Maranta arrowroot, and this is a case which often occurs iu trade, it is not taiily distinguished; the presence of the potato starch granules may be inferred by their size, but it must be remembered that there is no difference between a large Maranta and a small potato granule. There is, however, another mode of discrimination; the potato granule is ntrongly marked with concentric rings round the hilum—the Maranta granules exhibit this property in a much less marked manner; and again a few of the granules are too largo to be classified as Maranta, and some of them are less regular in form.
On taking a Bample of flour and magnifying it 200 diameters we find the granules marly the same ; in fact, to the tyro it would be the same, and the sample would be passed by as pure. But if they are only nearly tho same, and not quite identical, there probably is a mixture of barley with tho wheat. Fig. 2 Rhows a sample
he can mount parts of it, that is all. Heat must be applied to the balsam to melt it, tho object placed in it; air bubbles -withdrawn by an air syringe ; the thin glass cover put on and set aside for some hours. Very small insects, as the diamond beetle, may be mounted in a small box, so that the insect is exposed when a glass lid is withdrawn; but this is only done when tho wing cases present a surface worth lookingat. Seeds should be soaked in turpentine; petals may be mounted in water cells containing camphor. Zinc rings are the best for beginners to manage, the gold size takes easily to the surface. Glycerine is also very useful in mounting vegetable tissues.
Art Degrees, ic. [4856.]—"Beriro," if he is anxious to graduate,, must do so at the London Universitv. He mnst produce a certificate to show he is over lixteea years of age, pay a fee of £2, and go through a matriculation examination, held at the University of London, or at Owen's College, Manchester, Queen's College, Liverpool, or St. Patrick's College, Carlow.
The candidates for examínate n are examined in the following subjects :—Arithmetic, algebra, geometry (theoretical), the first fonr books of "Euclid," mechanics, hydrostatics, hydraulics, pneumatics, and optics, inorganic chemistry, Greek and Latin. The examination of Jan. 9, 1871, will be from the following books: — Xeuophon, "Cyropiedia," lib. ii. ; Virgil, "Georgics," lib. ¡ii.; ".Eneid," lib. iv. June, 1871, Homer's " Diad," lib. ix.; Cicero " Orat. II., in Catilinam." Besides the above, English language, English history, modern geography, and either the French or German language, at the option of the candidate. If "Beriro" passes tho examination, after one years' studv he is admitted to the higher grades, or examinations for B.A., M.A., D.Lit., B.Sc, D.Sc, LL.B., LL.D., M.B., M.D., *c. These are not given in the results of one examination ; two examinations arc required, except for the "Doctor" degrees, when three are requisite; and two years must elapse between the completion of "Bachelor" degree and the examination by which the Doctor's degree is obtained.
Iu query 4404, "J. M." asks for a sketch of Griffin's (Griffith'sbumer he says, but I suppose he means the well-known Griffin'B furnace) burner, and wishes to know how the blast is arranged. Griffin's furnaces are arranged for heating either at the top or bottom. Tho enclosed is a rough sketch of the burner. The
diameters. In barley flour we see more cellular tissue than in wheat flour, "and the granules of starch are more often found enclosed in their colle. When a black or dark mass is seeu, instead of using the needles and tearing it to pieces we may admit iodine water—this blackens the starch and only colours the cell tissue slightlv yellow; on turning up a strong light, the object is clearly depicted. Portions of the husk and needle-shaped fragments are also seen in barley flour which are never seen in ordinary wheat flour. Exceedingly small granules are also seen in this flour as in wheat, and of the same form, with the exception that the hilum is more plainly seen. Fig. 8 is a sample of beau flour, which Dr. Hassall
affirms was found in a sample of " cones."
The grannies thomselves are very peculiar, being irregular in shape, and being marked with an elongated and deeply furrowed hilum. Cellular tissue is also seen, and there is a strange absence of the small granules which would answer to those of wheat and barley flour. ....
By the irregular form of the granule this kind of adulteration may be readily detected, but, strange to say, I have never had the opportunity of viewing it side by Bide with wheat flour in a commercial sample. The cut (Fig. 3) was mode from a eample of beans, reduced to a fine powder by means of a file, which method answers exceedingly woll for preparing samples of flours in tho pure state for the purpose of practice in microscopical analysis.
"Sabbas"  wishes to know what sort of a microscope to purchase. I should advise him to invest ±'5 in one of Cionch's instruments, with a Jin. objective ; this will show starches as the figures in this letter, and is nearly as good as one of Rose's instruments. If £5 is too much, get Field's " Society of Arts " Studout's microscope, price £8 15s., with powers from 50 to 200 diameters; this is not nearly so good as Crouch's, but is a very good instrument.
In answer to"C. R. H." , he cannot expect to nionnt such an object as acricketupon a glass slide;
air is supplied by a blowing machine, and a pressure of water upon the gas of Jin. is sufficient. The furnace for heating at the bottom is arranged thus:—A, crucible jacket, crucible, and cover is pi iced upon a flat plate resting upon an iron stand. The lifter is then placed so that the crucible shall stand in the centre A plumbago dome is then placed over the crucible, restiug upon the lifter; tho f urnace is then built up with clay cylinders, and nearly filled with water-worn pebbles. When ready, the burner is connected with the gas on one side and the blowing machine on the other. The gas is lighted and pushed into its place in the flat plate whereon the crucible jacket rests. The blast of air is then sent in, and the progress of the operation can be watched by removing a plug in the lower cylinder.
For heating at the top—which arrangement, by the bye, is much the best—the perforated flat plate is placed as in the preceding, bat instead of the lifter а cylinder is placed next. Over the perforation at the bottom is placed a hollow cylinder with holes in the sides and a solid top. Solid cylinders are now placed to the required height, and an outer clay cylinder placed in position. The annular space is then filled with pebbles, and a perforated flat plate placed on the top when the crucible and cover in its jacket has been arranged ; the gas is then lighted, as in the former description, and allowed to play on the crucible before being thrust into its place, otherwise the cylinders will crack or the gas go out.
Possibly it may be unknown to "J. M." that Messrs. Griffin & Sons issue a guinea oil lamp blast furnace for melting metals. It will melt lib. of catt iron in twenty minutes, by the use of threepennyworth of oil at 8s. per gallon. The blowing machine is charged extra.
Chemical.—The reason "Prussian Blue"  failed in attempting to make potassium ferricyanide was passing the gas into the solution too quickly, the solution was too concentrated, or ho allowed the liquid to get hot. The grand secret, if there is any in the matter, is to cool the chlorine before it reaches the solution ; to pass it in alowIii ; and, above all, do not add chlorine in excess. The end of the operation is determined by the solution giving no precipitate with a ferric salt. By acting on a dilute solution, and afterwards evaporating down to" crystallizing strength, the potassium chloride is leftwith a little of the ferricyanide in the solution, while the greater part crystallizes out. This is the method I have always employed, and Ьате found no difficulty in obtaining a
pure salt. If, however, the temperature is allowed to rise, or chlorine passed in excess, hydrogen chloride- is formed, and a-» this latter acid decomposes tho salt ata high tempérât are, the operation is spoiled. I have seen students trying to prepare this salt when the solution has been actually boiling from tho hot chlorine introduced. George E. Davis.
GALVANIC BATTERIES. — SLATER'S IKON CELL.
 Sir,—The clear and interesting description yougave the readers of your inestimable weekly by calling their attention to the subject-matter of а patent iron battery electro-magnetic engine, induced me to test their power in many ways, and compare the amount of work they would do, at what cost, taking the saute number of cells of zinc and carbon (ordinary Bunsen battery), each having the same «.mount of uni-face exposed to tho excitant. The result has far exceeded my expectation; and my great astonishment is that it has been so long kept from the public generally, or so very little notice or mention of iron as such a powerful element when used аз a substitute for zinc.
I have read carefully most of the letters on electricity, sc, "given by that most worthy eontribntorto your pages "—''Sigma ;" and although I cannot endorse all he says respecting this "Slater's iron cell," I have nevertheless to thank him for the careful and comprehensive method stated as the result of his experience. 1 will now proceed to explain the amount of absolute work done by the iron and carbon battery in 25 hours; ditto zinc and carbon (Bunsen), 25 hours; each a series of 24 connected to its voltameter and from thence to two gasometers.
At the end of an hour the zinc carbon had 42 cubic inches of the mixed gases (decomposed water* more than its rival; in 2 hours, 5.; cubic inches only more than the iron; tho 3rd hour tïieiron took the lead, and stood 34 inches ahead of the zinc; 1th hour, 76J ; 5th. 115; 6th hour, 160J; 7th hour, 214; Sth hour, 275 inches more than the zinc carbon. At this time I was compelled to leave them until the expiration of the 25th hour, when the iron carbon had the advantage by 1,762 inches.
There was considerable energy in the iron and zinc at this time, hut the Bunsen was exceedingly feeble,.a* the galvanometer showed a deflection of only 14", while the iron stood at 37 '. I had previously weighed the metal before commencing. The zinc had lost 9 ounces more than the iron and required 5 plates to be re* amalgamated.
Experiment No. 2.—I resolved to try them another 25 hours, again to compare their work and comparative cost, which were as follows :—
В UN SEN. H. d.
Nitrons acid, 30lb. at 4d 10 0
Sulphuric, 61b., at l.Jd 0 9
Mercury for amalgam 0 0
Lad—attendance to ditto 1 9
Slater's Cell.—The density of the fluid in porous cells had considerably weakeuod, and took 271b. of the mixed nitrate of soda and sulphuric acid to get up its standard strength of 14'oÜ. The cost of this, as I buy the material, amounts to about tho same as sulphuric acid alone. The addition of water to dissolve the soda brings it within a fraction—namely:
271b. at 1Ы 8 4¿
Attendance 0 G
or 3s. lOJd. against 12ч., — being an advantage of more than 8s. in favour of the iron cell, saying no tiling of the extra work done by the iron. The result of the second day's trial was more in favour of the iron, more gas being liberated and much more zinc lost by local action. Indeed, some of the plates were used up, while the iron showed no sign of ill-usage beyond a uniform thinning. I find no use in making the solution in contact with the iron very stroug, as there is a useless evolution of hydrogen with but little extra power; and when the porous pots have been used a few days I do not find that the solution rises in them as "Sigma" speaks of.
Sea-water is a uniform and excellent excitant for the iron. I am using this battery for an electric light with great satisfaction ; and am sure that when its great power and the cheapness of the working cost is made known it must become a great favourite.
A*t I must not trespass further now, I will, if agreeable to your readers, send tho result of further experiments with a series of 30 cells. I wish you and your scientific contributors every success. Omeoa.
BICYCLE BIDING AND WALKING.
[19^1 Sir,—As various letters on the "Bicycle" have lately appeared in the English Mechanic, all very much in favour of this new machine, I think a few words from myself—I having been in coHtinual practice for over twelve months—may be of some interest, and save mnch disappointment to those of your readers who are about to learn.
Some time back, at tho first introdnction of these machines, I, Herman Slomau. and others, while advocating the use of them for amusement and exercise, deprecated their utility for practical purposes or economising force. A correspondent at that time calcu
lated theoretically the difference between bicycle riding and walking; he concluded an elaborate calculation proving that the force necessary for walking a distance, вау five miles, if put into use on the machine, would only carry three miles, or little over two thirds. These calculations were based on the fact of the bicycle not taking the rider, hut vice ver*á, the rider puehing the machine, of wVieh, by experience, I аш painfully aware.
I have travelled most of the Surrey aud Kent main road'-, and find (with the bicycle), taking the roads as they come, aud using force enough to thoroughly exhaust myself on a twenty mile journey, an average of about four miles an hour to be the outside speed, I can continue tho journey—this being less than my walking pace*. The machine I ride is a ¿Sin. wheel; my height is 5ft. lOin.; weight 11 stone. On a walking tour I manage generally to do about 30 to 40 miles a day, which, up to the present I have not been able to do on tbe bicycle; although, had I trained twelve months for a walking expedition, I am satisfied 50 nulos within the 24 hours would be rather under than over my power of endurance. My experience makes me believe that those of your correspondents who write of travelling 15 miles au hour on the bicycle must either be joking, or totally unacquainted with the subject. I will admit that on a level asphalte road, say a quarter of a mile round and perfectly level, a very high rato of speed maybe obtained; and so it is with the locomotive, which ou a plain road travels at 10 miles an hour, but on rails, where the friction is reduced to a minimum, 40 miles is done easily. I therefore consider the bicycle a toy, and only fit for exercise; although there are some men particularly fitted for these exercises, which perhaps may explain some of the astounding feats of which we read; but I find, on enquiry amongst my friends, that the majority join me in discarding the machine for all practical purposes.
If enthusiasts think it necessary to have a manual machine for ntiliziug force, I cannot recommend them anything better than a round wire cage similar to that of the squirrel; by imitating the movements of that industrious little animal, they may product motivo power to their hearts' content. A wheel-barrow, also, would do, but has the disadvantage (as some bicyclists say) of not utilizing the weight of the bod}'. I can quite agree with your sensible, but facetious correspondent, "\V.," who on a long journey thinks it better to carry the bicycle; and I am perfectly satisfied, joking aside, that on ordinary hilly and dusty roads it is much easier to walk behind and push the machine with the hands than to mouut and force it forward by using both hands aud feet. Iï. (i. Bennett.
 Sin,—Yon will be as well able as any one to judge of the expediency of my proposition, and hence it should interest you to insert my letter. There are many of the readers and subscribers of your journal who are constantly wanting to send small sums to you, to their tradespeople, to their children at school, and to their correspondents at home and abroad ; and the same applies to the world at large. Now, stamps are troublesome to all parties, and a temptation too strong for many postmen to resist, aud a ;îd. Post-office order is a heavy tax on fid. to 2s. 6d. Hence, I would ask, could not a short aud counterpart ticket system be adopted by the Post-office authorities, at £d. or Id. charge, to bo more convenient and saf<-r to the public. And again, as an old colonist, I have often to write for advice, and often to those who don't like, to pay Gd. to oblige me; and which I quite as mnch object to their doing; butas our stamps are useless there I do not like paying 4d. or Cd. to send out (id., and therefore do not sometimes get replies, of course. And I am but one of many tens of thousands, aud I say tho public servants ought to study tho public convenience and interests in some suitable way; but by your inserting the above it may lead to a useful consideration of the same.
L. Hewettjc and M. Engineer.
 Sir,—In looking over the pages of our Mechanic this week, щу eye caught a letter headed "Musical," iu which my uauic figured; audi naturally expected to find something interesting aud instructive, at least for myself. I am sorry to have to say that I was disappointed. I do not wish to be harsh to any of our correspoudents, but why should people write upon subjects about which they evidently know nothing? Nearly the whole of the letter is йimply unintelligible to me. The part commencing " aud why should signatures," aud ending "flats or sharps," is particularly obscure; and after puzzling over it for half au hour, I am almost inclined to follow the example of our excellent " F.R.A.S.," aud offer a small prize to any one who will discover what it means. "Music" seems to think that something " ought to bo glaringly apparent" from his arguments (?). Perhaps it is all clear enough to him—I can only say that I do not understand it. Then there's the question:—"What remains of the seven, being flats or sharps." I'm sure I will not pretend to say; perhaps "Music " will kindly give your readers the interesting information. Will "Music " tell us something further about "the very effective mode of marking expression by joining the stems of tho notes," as it is possible that some others of our readers, like myself, may never have heard before of such a mode of marking expression? "Music" first enquires what is the oriiiin of the stave, and then immediately assumes that without doubt "it represents the strings of an instrument," ¿i.e., on which (wrong) assumption he pro
MR. BUDGE'S AIR PUMP.
 Sir.—Will your correspondent, Mr. Raai?, have the goodness to give some description of Ms axr pump? At present, we are indebted only to yon asd Mr. Taylor's engraving for а ven good elevation af tie instrument, but this, ior ¡rraetieal тел. is comparativ^iy worthless ; and as the greater part of your reader* er> practical men, it is a great desideratum tixat all is formation should be of that character in order that it may be useful.
He says, "And as yon will see, from the phoio«. bringe the mercury down to tho 30th part of an inrb." Now if the pump will produce such a varanm, tbcmgh I do not see how the *' photos " can show it, then it wül do what few pumps will do.
What does Mr. Budge mean by " a metallic planner mechanically fitted?" I have not the faintest conception. I know what "metallic pibtnns" are in the general scientific use of tho term, bat they are. qnik inapplicable to the air pump. Again, how a ** status^ box " can be " composed of twelve collars of leather" I cannot comprehend; or in what way tho ** оД chamber," "the piece of hollow brass," the iv other pieces of leather," and the "end of the gland" are connected, I am quite at a loss to discorer. A^ain, b¿ speaks of tho valves; but he does not say e*ie/ paires, or where they are situated ; and there is во indication in the drawings, admirable as they aw, to sbow where or what they are.
From the position of tho pipe leading to the cylinder I opine that it is on Tate's plan, bat I should be gi&d if the maker would give a more «peoal and a<*corate* account of the pump internally, the «Xenial cot-truetion being sufficiently clear from the ^uïTiviass, Will he also be good onough to state the kind ai ш1 sukhc uses and where procurable; what kind of où he osea-, and how the piston is oiled?
I shall be happy to answer any enquiñe* ou the subject of my coU. 1эт>рстошст1
MR. PROCTOTt AND MB. LOCKTE«.
 Sir,—I thank 4,Luke the Labourer" for not "wishing to be hard" upon me. He is most mcrcilaL and considerate. Yet I should deserve no mercy what* ever if I had really acted as bv sapp*»sos. To begin with, I could not even plead ignorance, for I hare read all Dr. Dick's charming works on astronomy* Bat even if not, how could so obvious a fací as the concealment of the sun from certain parts of Saturn by the ring system—a fact which every oatwho has looked at the pianct through a telescope can ue for himself— become the subject of a reclamation. The notion is preposterous, and had I mndo so ludicrous a claim 11 Luke the Labourer" might have been hard upon nie with a vengeance.
Premising that I charge Mr. Lockyer with nothing worse than forçetjulneti, I will now submit to your readers the passages from my " Saturn and its System" aud from Mr. Lockyer's "Elementary Lessons of Astronomy." After referring tí» Table XI. ( forming two, octavo pages closely crowded with figures, which I was occupied seven weeks in calculating, and every detail uj which ten* absolutely neir), I proceed—"From this»table it will be seen that . . . (for instance), in latitud» 40 (Saturnian), the eclipses begin when nearly three years have elapsed from the time of the autnnmaJ equinox. The morning and evening eclipses contasse for more than a year, gradually extending until it* sun is eclipsed during the whole day. . . These tottl eclipses continue to the winter solstice, and for * corresponding period after the winter solstice; in aft, for 6 years 2361 davs, or 5543-0 Saturnian days. This period is followed by an interval of more thau a year of morning and evening eclipses. The total period during which eclipses of one kind or another take place is no less than 8 years 2ifc!-H days. If we remember that latitude 40 on Saturn corresponds with tho latitude of Madrid on our earth.it will be seen how largely the rings must influence the conditions of habí lability of Saturn's globe, considered with reference to tho wants of beings constituted like the inhabitants of our earth."—*' Saturn and its System," p. 1H1.
In the "Elomentary Lessons of Astronomy," Art 270, Mr. Lockyer writes:—
"In latitude IU we have morning and evening eclipses for more than a year, gradually extending until the sun is eclipsed during the whole day . . . and these total eclipses continue for nearly seven years; eclipses of one kind or another taking place for H years 292 days. This will give us an idea how largely the apparent phenomena of the heavens and the actual conditions as to climate and seasons are influenced by the prusence of the rings."
Aud, as I said in tho letter on which " Lnke the Labourer "comments, there* is nothing to show that