SCIENTIFIC AMERICAN SUPPLEMENT, No. 387. 6173 and more easily regulated tban others. It made part of a SIEMENS' EXTERNAL ARMATURE MACHlNE. circuit, which included, in addition, a pile and an induction bobbin. and tbe tine wire of the bobbin was connected witu IN addition to tbe different dynamo-electric machines tbat a second telephone. To the plate of this latter there was have come into use, there is a certain number of types whicb likewise fixed a micropbone, included, in the "arne way, in

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... e based upon very ingenious ideas, and which have never· the circuit of a pile and a bobbin. The induced wire of this tbeless remained in tbe condition of experimental apparatus. bobbin was connected with a tbird telepbone, and so on. I Tbese latter, in spite of their want of success, are in teresting employed in tbese experiments only three teh'phone-micro-to know about, either because tbey point out a new road that phones; tbe fourth, which was of the ordinary style, served has heen incompletely stndied, or became they show, on the for receiving tbe re-en f,)rced sound, and wasplaced in a dis-contrary, a road that should not be entered upon. tant spot, separated by several rooms_ Among such apparatus may be mentioned the Topfmas-"Tbe following are tbe results obtained with this ap-chine of Mr. Siemens, concerning whicb we have already paratus: said a few words. We shall first recall its principles. If "The muscular current that operated the first telephone set we have a magnet with two 10ngilUdinal poles in front of in motion, at the Hame time, the microphone tbat was ad-each of . wbich ther," passes a conducting wir � . tbere will juste(t to the telepbone plate. t1evel ? 'p lD each of the two cond ? ctors , two opposIte current � . " If tbe microphone is properly regulated. there is always But, If . t . hese condnctors are uDl�ed WIth each other by . tuelr obtained a sound which is a little stronger in the secon d lel-extremItIes, so as to form a helIx, the two currents WIll be ephone than it 'cas in the first 'fhe. second mi c r ophone will ' added to each other. If, then, w . e revolv � tbe helix around re-enforce again the sound transmitted, and in the tbird i t �he magn:t, 'Ye shall bl;..able, on lIlterP?S lDg a commutator will be yet �tronger, and so on. In my experiments, made l�tO t�e CIrCUIt, to obtam a current havmg always tbe same by the aid of tbree telepllOne-microphones, the sound was so dlrec �l On. . ., . . strong in the fourth telephone (provided with a speaking Tbls macbme, w�!Ch Ylelde . d but I , l . ttle . electro-m?t:ve trumpet) tuat it could be heard very distinctly at a distance force, and had . a resIstance 'YblCh was .1keWIse very shg�t, or �cveral meters. On placing a watcb upon tbe first micro-s�ems to have 1lI . splr�c1 Mr. SIemens to construct a macbme phone Ill btained in tbe last receiver a sonnd analog o us to lIke that 8hown III FlgS. 1 and 2. that of the drum. " In tbis apparatus Mr. Siemens has rendered the iliduced ring stationnry and caused the inductor to revolve-the in ductor in this case being an electro having the form of a double T iron 'armature (Fig. I), ON THE RE-ENFORCEMENT OF SOUNDS TRANt:; MITTED BY THE TELEPHONE AND MICRO PHONE. The armature is formecl (Fig. 2 ) of a series of groups· of wire wound around an iron cylinder. The wires of the different gr,mps end in the radial pieces of a hollow collector, and internal brnRhes, B B', ·put them in connection with the internal movable electro. Supposing that the wires that are attached to tbe termi- nals, P, of tbe movable electro are united with each other, and that we revolve tbis electro through the medium of a pulley affixed to the axle; tben the remnant magnetism of tbe double T iron armature will induce currents rn the ex ternal wire8, and these currents, gathered up by the brushes, B B', will re-enforce tbe revolving inductor, and, after a cer tain length of time, tbe current se , t up will have reached its full intensity. , .• 1 ' It goes witbout saying that tbis machine is capable of Fartber on, Mr.',;W-oukoul{)ff says: " I am unable to con-working inversely as a motor, without, however, presenting tinue my experime,nts with regard to the application ofthis I any advantage from such a point of view. apparatus to tbere-enforcement. of. all the sounds transmitted Pig. 1 shows how two,fubbers, which correspond to two by the telepbone alid microphone,' so I publish what I have rings tixed on the axis of ther€vol'ving armature, permit of don�jn hopes that some one else will take up tbese interest-collecting the currents set up. or of introducing the current ing' rcsearcbes." • when the apparatus is employed as a motor. Desirins to verify tbe results obtained hy IMr. Woukou-It will be seen that this macbine is in fact only a reversed ,loff, espeCIally becduse they are.in contradiction to the prin-Gramme macuine of elongated form, and it is easy to under ciple of the conservation of energy, I have made the follow-stand tbat tbis arrangement canllot prove favorable for a raing experiments. tional production of a curren t. Tue annexecl figure shows the apparatus that I used, and Tbe inductor being of limited dimensions with respect to which is identical with the one employed by )1r. Woukou-tbe armature, from tbe fact that it must be continuolls in loff. I took two piles of different forces, two induction bob-the interior of the latter, t be intensity of the magnetic field hins of different resistances, and micropholles of different cannot pos&iblybe increased beyond certain limits, and tbere sensitiveness and resistances. I reversed the position of the will always resnlt a marked inferiority. bobbins and piles as well as lhat of tbe microphones and On another hand, the arrangemeut of the induced wires telephones, at different times, and I constantly obtained tbe iu the magnetic field is likewise less favorable than when following re:;ult: The vibrations of the piau! in the telephone, tbe armature is within the latter, and this is anotber reas on t', were much more feeble than were those of the one connected why the arrangement is not advantageous. The machine, directly byfine wire with the fine wire of the bobbin, B. tben, seems to us to belong to the category of ingenious At all events, this experimellt in no wise confirms the the-ideas that are not destined to become the object of a real ory of Mr. Woukouloff thnt I set out to verify. -P. Golot�-application, but which present nevertheless a certain hislorie bitzky, in La Lum�' ere Ekctrique. interest.-La Lumiere Electrique. FIG. 2.-· SIEMENS' EXTERNAL ARMATURE MACHINE. IT is now cleal'ly and.generally understood tlIat the aB-pre· vailing cesspool used for tlIe disposal of household wastes is in every respect pernicious and objectionable. It would hardly be t. oo strong a statement to say that the hest cess pool is worse than the best sewer; even wlIere water closet matteris excluded, the condition is not much improved. Thus far the cesspool has been the only meanS of disposal generally available where there were no sewers. The slowly growing and carefully matured experience of the past fifteen years has, however, demonstrated the suc cess of the system of sub-surface irrigition, or tbe disposal of foul liquids by opening jointed drain-tiles laid neal' to tbe surface of the ground, within reach of the roots of vegetation. as not only a very great improvement on the cessp()ol, but as being, in fact, . as nearly perfect IlS the cOI:ditions of the case will probably allow. This system originated, so far as we know, with the Rev. Henry Moule, of England, tbe inventor of the earth-closet, who puhlished a description of its application in 1868. He had found tbat the use of tbe eartb-closet was objected to for the reason thllt it falls to provide forthe disposal of the liquid wastes of the bouse, leaving it necessary that a cesspool or sewer should be resorted to for tbis purpose, wbich might as well be also u�ed in conn ection witb water-closets. He tried tbe experi ment of laying an open-jointed tile drain a few inches below the surface of tbe ground along the foot of a trellis covered with grape vines. The result was a vigorous growth and an improved fruitage of the vines, and an inoffensive and innoxious disposal of tbe waste liquids. _ A few years later, MI'. Rogers Field mude use of the same 'system in connection with tbe drainage of honses at Leather head, supplemenling the drains with a flush tank arranged to bold back the flow until it became full, and then to discharge it with one rush into the tiles, effecting thereby a long period of intermission, during which tbe soil was exposed to aera tion and consequent purificati on, avoiding the constant satu ration that a steady trickle from the honse-drain would produce at the beginning of the drain, and bringiug its wbole length into equal requisition at each periodic outflow. In tbis form the apparatus was somewbat extensively used in England and elsewhere. At my own bouse in New port, wbere about two hundred feet of absorption tiles per formed their office sll.tisfaetorily for eleven years, I inter posed a settling basin of ahout one hundl.ed gallons capacitv, III the course o"f the drain leading from the flush tank to tile absorption area. This held back coarser matll'rs and a hlrge p r oportion of tbe gre· ase;. There was, however, always some dlfficulty resulting from the adbesion of grease to tbe outlet of the flush tank, requiring frequent cleaning of tbe siphon, and, later, such a disturbance of the accumulated matters in th e settling basin as caused flocculent and greasy particles to flow-forward, and in time to cboke tbe drains. It became necessary, from time to time (three times in the eleven years), to lift the whole series of tiles, wash them, and replace them. The next improvement was to place the settling-basin lJe tween the flush-tank and the house, serving as a grease-trap, protecting the. siphon of the· flusb-tank agninst the gradual accretion of grease, and leaving on ly a rela. tively deal' li· quid. to be ' discharged into the pip esc Tbis was a great im provement,and practically effected all tbat was necessary where only the' suiall' flow 9i the kiteben sink was to be taken care ·bf. It was fouud; how ever, when it became a tJ.uestion of disposin g of the entire waste of a house, in cluding w,lter-closets, batb�, etc. , that the flow into the settling-basin had at' times sufficien t force so to disturb its deposits as to cause a cOllsiderable amount of semi-BOlid matter to pass ove r into the flush-tank, leading in time to the obstruction of the drains. This has been remedied by constructing in the settling-basin a division-Viall at right al) .gles to the line of flow, and built to about the height of 1he ordinary water-level. . Tbis wall, dividing the btsin into two chambers, confines the disturban ce caused by the inflow to the first chamber. . The flow from this into the other chamber, being in a tbin stream over the top of the wall, does not disturb the deposits, and only the liquid passes into the flush-tank. It has also been found that, whatever precautions might be taken, it mi�ht become neceFsary from time to time to take up parts of the absorption drains, to cleanse th�m from occasional obstructions. When such removal of the tiles becomes necessary, it is of the grelltest importance that they should be relaid on their exact original grade. To the end that this removal and cleansing may be performed by any laborer, and in an inexpensive manner, it is desirable that the tiles be laid on a foundation tbat need never be diRturb ed. Strips of board serve tbis purpose well whilf' they last; but tbeir decay is somewbat rapid under such conditions, so tbat it is best in constructing the drain to lay first !I line of earthenware gutters, carefully placed and never to be disturbed, and tn lay tbe tiles in these. . Furthermore, whatever precautions we may take to pre vent flecks of greasy matter from entering the drains, small amounts of such material will inevitably be carried forward witb the discharge, so that if the tiles are laid witb close joints, the ends actually touching each otber, the nnrrow spaces, whicb serve a good purpose at tbe outset, will in time become choked with deposits, causing the drain to act as a tight pipe, except at tbose few points where, f;oom breaks or other inequalities at the ends of the tiles, there is an Unduly large opening. When the drains are in this con dition, tbe escaping sewage confined to tbese points, under the pressure of the discharge from the tank, may here and there reach the surface, which is_of course objectionable. To avoid this difficulty it, is now my custom to reqnire the tile layer to carry a pIece of tbick sole leather as a gauge. laying the drains witb a distance apart equal to tbe tbickness of the leather. Here again might come anotber difficulty: were sucb open joints allowed to remain unprotected, the covering earth would work througb tbem into the tiles and cause obstructions. Tue joints are therefore covered with a short earthenware cap over the-top' . In' order to leave the space between tbe tiles as effective as possible for the escape of the sewaglJjl the gutter and the cap are both made with a radius greater than that of the I outside of the tile, so as to form a true bed and an efficient cover without hugging the joint, except at tue very top and bottom. These developments of the system, simple though they are, have been slOWly worked out to meet the succession of difficulties which have arisen in practice. They have now had sufficiently long application and sufficien tly extensive trial to make It prudent to assert the practical efficiency of tbis method.