Kindly keep your Queries on see Date sheets of paper when corresponding about. It such matters as patents, subscriptions. books, etc. 'rhis will greatly facilitate answering your questions, as in many cases they have to be refel'l'ed to experts. The full name and address should be given on every sheet. No attention will be paid to urigned queries. Full hints to correspondents are printed from time to time and will be mailed on request. Prime Movers and Their Accessories. N. RO''ARY IDNGINID.-T. IDZAL, Camdcn, J. An object here is to provide ! novel form of engine in which a single rotary piston is actcd on at several £loin ts in its rotation by thc admission of fresh ail. Mcans are provided for operating the abutment valves, so as to insure the greatest economy in the workings of the engine. Means provide for controlling the exhaust ports. Thc inventor accomplishes this liy a series of valvcs whose position may be simultaneously adjusted by the manipulation of a single lever. A further object is to providc means for regulating the steam inlet. Railways and Their Accessol·jes. NU'i' LOCK.-CI,AUDI B STILLWI<,L, P. O. Box 522, Savannah, Ga. This invention relates to nut locks, and is particularly applicable to the construction of such devices when used in s"cllling the nuts of the holts which attach the fish plates to the rails at the mil joints. It constitutes an improvement on the devicc No. 880,9:'W patented uy MI'. Still· WANTED. LOCAL REPRESENTATIVE W A NT E D. Splendid income assured rilht man to act as our representatIve atter learning our business t boroughly by mail. Former experience unnecessary. All we reqUIre is honesty, abIlity. ambition and willingness to learn a lucrative business. No sQUcitmg or traveltn/. 'l'his is aD exceptional opportunity for a man in your section to get into a big paYing business without capital and become independent for life. Write at once for fnll partlcnlars. Address, E. B. Maraen, Pres. '!'be National Co-Opera. tive Real Estate Company. L 318, Marden Building. Washington. D. C. MISCELLANEOUS. .. CAN ' 'HE SCIENTISTS BE MISTAKEN?"-Astounding theories,-solid baSis tor Kilvin's theory of vortex motioll. Matter doeR not ( hold” together. * attract,” ' repel,” act at any distance, or act without contact. No “ potential” energy. Only one ultimate ele . ment, aether. M ome ntu m (motion) of aether. basis of all energy, (and phenomena); mY, true energy measure. “ An Amazing Calculationj” perpetual motion (tbeoreti .. cal) based upon system of levels. Orbital vortex motion ptfet^nTentl9(eotaV: ^ac.ic!a'es:Wu:! 'n: Pam- FREl-"INVESTING FOR PKO F I T Magazine. Send !e your name and [ will R ail you this W; g :ine absofutely free. ae:ore you inl:st a dollar anywhere -get this magazine -it is worth $10 a copy to any man who intends to invest ft5 or more per month. Tells you h:[ rJ ,000 Ciin )ro; to :22i{bO: —how \o judge l ;fferent classes Oll iJ;estments; the Real Na 2 2 ing Power of your money. This mal8zine six months free if you write to·day. H. L. Barber, Publisher. 423. 28 W_ Jackson Blvd . . Chicago. MAKE BIG MONEY operatin” a D a y da rk Post Card Machine. Pboto postal cards made and delivered on the spot in ten minntes In the open street. No dark room necessary-it does not require an experienced photographe r to make first·class pic tures. P ays a grosds : ?fit of 500 per cent. ;Orite toda: W :{ rV samlle and catalogu:n f' ydark Speclalty go., Dept. V, St. Louis. MOTORCYVLES CHEAP.-Send to·day for free oatalog 01 new and used motorcycles. Algo motorcycle accessories and attachable motor outfits for converting bicycles into motorcycles. Shaw Mannfacturing Company, lept. 2, Galesburg, Kans. GINSENG Raisin” is t he snrest way to make Big : \ol lney o n L ittle Capita l. O ne acre wiill yield 5 0 lbs. Sells at $6 a lb. I will bu y all yon raise. Gro ws a nywhere. Requires your spare time only. Tf you are not .atlsOed with your present income. write me today. T. II. Iutton, 780 Sherwood. Ave., LouisVille, Ky. well. In the present case, the invention contemplates the use of improved mean for :re: venting the nut from rot:ting on the bolt, and the principal object of the invention i to provide means for covering the mechanism of the device so as to prevent it from being injured or displaced. The illustration in the larger figure represents a side elevation of a Tailroad rail joint showing a modified form of the invention; and the smalier is I pcrspectlve vicw of a modified form of the lock plate. CAR STAKI POCKI'.-CHAltLES FLINK, Ironwood, Mich. This invention refers to load·retaining means for vehicles, and especially to means whereby side stakcs are positioned upon platform and logging cars, and-which Ilay be held in vertical position agaJnst (12522) H. L. W. asks: What causes thc changcs of a barometer at a given point? A. 'rIle chaugcs of the barometcr at any given place arc caused by the change in the pressure of the ail above that place. The atmosphere has waves in it of greater and lcss pressure, and these waves move around thc earth, follOWing each other much as water waves chase each other ovel' the ocean. A high follows a low, and a low follows a high. A low baromcter has been tmced for ahout five weeks from the coast of Asia across the Pacific, America, the Atlantic, Europc, and into Siberia. While there are erratic changes thcre is also a general flow of areas of greater and of lcss pressure to which the barometer responds. (12523) A. E. H. asks: Some months ago you published in your Answers to Corre"pondents an explanation to show that if an object sinks at the surface of water, it will sink to thc bottom, no matter how deep the watcr may be; the greater pressure at in.. creasing depth having no effect to kcep the oujcct suspendcd. I inclose 10 cents in currency and postage. Will you kindly send me II copy of YOllr paper containing that statcmen t! 01', if you vrefer, republish your answer in an cady issue, where I shall scc it, as I lJuy the ScmNTIFIC AMERICAN rcgularly. A. l hc qllestion of sinking or floating is determit(>d uy a law known as the Principle of Archimedes. It is that an immersed body is buoyed up by a force cqual to the weight of the fluid displaced. If a body under water weighs less than the water it displaces it will rise; if it wcighs the same as thc water it displaces it will rcmain where it is; if it weighs lIIorc than the watcr it displaces it will sink. And if it begins to sink and no change is made in it, it will continue to sink, because it is more COmlessible than water. If it is heavier than water at one level, still more will it be heavier than tbe water at a lower level, since in going to the lower level it has bccn compressed by the watel' more than the water itself has bcen. Our attentiou has lately been called to the case of the slIhmarine, which can bc held at a selected depth. But the volume and the weight of thc submarinc are changed by adilitting or removing water to adapt it to its desired depth, and it is made to have just the weight proper for the level it is to maintain. If it should begin to sink and no change were made in it, it would continue to sink to the bottom. It is no exception to the general case. The expression you use, “the greater pressure at increasing depth having no cfcct to kcep the body suspended,” is not quite corr:ct. It h:s an effect, but not enough effect To put it in another !ay, th! sinking body becomes denser more rapidly than the water does at increased depths, and so must continue to sink. This is one of the questions of frequent recnrrence. We reccntly gave the coefficient of cOlllpressiuility of steel, one of the hardest metals and least compressible. It will ue found in Vol. 124, No. 125, to which we refer for further statement. CAR STAKE POCKET the pressure of a load, or may bc easily released from a pOSition of safety. A further object is to provide a stake pocket capable of disengaging the stakc quickly without time beiug lost in cutting off the stakc close to the pocket, and thc consequent rcmoval of the short piecc thercfrom; and has for a furthcr object the provision of means whcreby any form of stake may be used, or in which a particular shaped set of stakes may be carried. The illustration show", the device applied to a car platform. NOTE.-Copies of any of these patents will be furnished by the SCIEN'lIFIC AMER I CAN for ten cents each. Plcase state the I.ame of the patentee, title of the invention, and date of this paper. (1 2 52 4 ) J. S . J. says : I am 'nstaIl .ng an electric bell clrcllIt wlth three bells and four cells attached. Will you please tell me in your Notes and Queries lines which is the most desirable-to connect cells in series, in multiple, or in serics multiple? A. Probably four cells in series will be sufficient to ring three bells, though only a trial can dctermine that mattcr. If it is not sllfci<nt, add more cells. ''he usual mode of arranging a bell battery is in series. When a sufficient numbel of cells have been put in series to give the voltage for the bells, YOI can get the necessary amperes by a second series of the same number of cells in multiple. A multiple armngement of single cells is not desirable. (12525) E. P. W. asks: If a Iocomoti ve drawing ten passenger cars running at a mte of speed of 40 miles an hour, should have every whcel of the locomotive and of each car securely locked at thc samc moment, would the momentum of thc tl'ain stop at the same timc? And what would bc thc probaulc effect on thc train by the locking of cach of the whecls at the. same moment? A. If thc wheels were locked by thc brakes so that they ccased to rcvQlve, the tmin would slide on the whccl rims until its momentum was exhausted. If you mean, however, that the wheels arc to be locked to the tmci( suddenly, we can only say that neither whecls nor car bodies,. nor any other moving particle, can ever be instantly stopped except by infinite force. that is, by a force greater than any known quantity. No moving train could have its momentum, instantly taken away; the attempt to do so has destroyed milch roiling stock In railroad wrecks.