Laman utama
Scientific American A Machine that Saws 240,000 Wooden Paving Blocks in a Day
A Machine that Saws 240,000 Wooden Paving Blocks in a Day
Boyer, JacquesSukakah Anda buku ini?
Bagaimana kualitas file yang diunduh?
Unduh buku untuk menilai kualitasnya
Bagaimana kualitas file yang diunduh?
Jilid:
98
Bahasa:
english
Majalah:
Scientific American
DOI:
10.1038/scientificamerican04181908-273
Date:
April, 1908
File:
PDF, 697 KB
Tag Anda:
Selama 1-5 menit file akan dikirim ke email Anda.
Selama 1-5 menit file akan dikirim ke kindle Anda.
Catatan: Anda perlu memverifikasi setiap buku yang ingin Anda kirim ke Kindle Anda. Periksa email Anda untuk yakin adanya email verifikasi dari Amazon Kindle Support.
Catatan: Anda perlu memverifikasi setiap buku yang ingin Anda kirim ke Kindle Anda. Periksa email Anda untuk yakin adanya email verifikasi dari Amazon Kindle Support.
Conversion to is in progress
Conversion to is failed
0 comments
Anda dapat meninggalkan komentar Anda tentang buku dan berbagi pengalaman Anda. Pembaca lain tertarik untuk mengetahui pendapat Anda tentang buku yang telah Anda baca. Terlepas Anda suka atau tidak buku itu, jika Anda menceritakan secara jujur dan mendetil, orang dapat menemukan buku baru buat diri mereka, buku yang sesuai dengan minatnya.
1
|
|
2
|
|
Scientific A.merican APRIL 18, 1908. for blocks and the supply of old A MACHINE THAT SAWS 240,000 WOODEN PAVING BLOCKS IN A DAY. son. director of the municipal workshops of Paris, has invented a block-cutting machine turns out 24,000 wooden paving blocks per hour. blocks are equally i rregular, for paving is done only in the summer sea BY JACQUES BOYER. M. Josse, the 273 These old blocks are scraped and trimmed for further use in winter. Furthermore, the demand for blocks varies from year to year. Mr. Josse, therefore, endeavored to devise a machine that would accommo date itself to all these irregularities, as well as to the sudden emergencies that are inevitable in a business that This ingenious and complicated mechanical· device will ad vantageously replace the machinery and inetholis now in use, effecting a considerable saving in wood as well as in labor . In the early days of paving with wooden blocks in Paris, the blocks were sawed with single circular or band saws. At a later period, in order to meet the increased demand, three machines containing four or five saws each were installed in the municipal work shop. Each of these machines consisted essentially of an oscillating frame, the lower end of which carried '1 number of saws, to which the planks were fed singlY by an attendant. In 1900 this equipment became in sufficient, and some more expeditious method had to be devised. It must be remembered that the daily output of a municipl!-l shop that turns out 25 million paving blocks per year cannot be uniform unless ex tensive facilities for ustorage. are provided. The trees are felled only in certain seasons, and the regularity of shipments is further impeded by the great number of purveyors and the uncertainties of the weather. Sometimes the manufacture of blocks has to be sus pended for weeks, in order to take care of daily ar rivals of R 20 or 30 carloads of planks. The demand View (If the Machine, Showing the Conveyor for the Planks. n; : �--� .------ �------� Longitudinal Rection of the Josse Block-Sawing Machine. of this character. The result of his studies is a huge machine 100 feet long, which divides each plank into 16 blocks by means of 17 circular saw!!. The planks are brought to the machine on platform cars, one of which is shown at the right of the dia gram. The length of each plank is a little more than sixteen times the height of a block, as it is laid in the pavement with its fibers vertical The width and thickness of the planks correspond to the horizontal dimensions of the blocks, when laid. Two workmen lift the planks, one by one, from the car, and lay them on a conveyor formed of two endless chains E, con· nected by transverse cleats. The chains run on sprockets 0 placed at the ends of an inclined frame A, and on rollers D, distributed along the somewhat convex surface of the frame. upper Two and sheet iron guides F keep .the planks in register and assure' their proper delivery to the horizontal table, to which they are elevated by the inclined conveyor. The planks are pushed along tbis table by combs K, of 16 teeth, attached to two endless chains which run on sprockets. The axes J J' of these wheels are mounted near the ends of a horizontal frame G, which terminates in two Emptying the Skips of Pavi ng Blocks. .& ll:AClIIlfE TRAT SAWS 240,000 WOODEN P.&vmG BLOCKS Ilf .&D.&Y. shafts, one of. which is free to turn in bearings on two posts H, while the other is supported by chains 1. front of each tooth of the combs is a spring L. In The 274 Scientific Amerlca.n. function of these springs is to keep the planks, before sawing, and the paving blocks, after sawing, pressed to the table. Near the end of the table where the combs and springs rise and abandon the blocks, the latter are held down on the table by a set of small wheels M mounted on springs. Each comb two 'little brushes which sweep all carries waste into holes at the sides of the table. The circular saws protrude through slits in the table. There are 17 saws, about 25 inches in diameter, mount ed on three shafts, of which two are in line with each other but not with the third, P. This arrangement APRIL 18, 1908. Hitherto the forest has been damaged by large herds of goats, which will not be prohibited from grazing in future but will be under regulation. The protection of the brush will conserve the water, which swells the Salt River and its tributaries and will help to develop the Salt River Valley. latitudes of certain locations, that they could scarcely be explained on the theory of errors of observation due to defects in instruments or lack of accuracy in observers. But before saying more on the aspect which the matter has now assumed, it will perhaps be interesting •. e· • to glance a moment at the question of latitude as it IS THE AXIS OF THE EARTH SHIFTING 1 appeared to the ancient Greeks. In the first place, cer BY J. F. SPRINGER. It has been known for hundreds of years that the axis of the earth is continually changing its direction. To be clear .as to this, recall that there is a point in tain of their philosophers distinctly taught the globu lar character of the earth. They were familiar, too, not only with the conspicuous daily apparent motion of the sun from east to west, but with his annual was adopted in order to avoid the excessive vibration apparent motions north and south. of a day when he halts in the constellation Cancer, having single shaft as long as the planks, bearing 17 saws and making 2,000 revolutions per minute. The accomplished the end of his northern journey. s long shaft could not be stiffened by intermediate bear They noted the is the summer solstice. This An imaginary east-and-west ings because of the small distance between the,. saws. line through a point on the earth immediately below It was therefore decided to distribute the. saws among this position three short shafts not in the same line. Cancer. Each shaft of the sun they termed the Tropic of It was said that a well in Syene was found is mounted on ball bearings and is driven by two belt to be such a point. wheels, one at each end. summer solstice the sun shone down the tube of the The bearings rest on iron Here at noon on the day of the well. Possibly it was from such an .observation that Syene was supposed by them to be on the Tropic of beams imbedded in masonry. Directly under the saws, in the cellar of the build ing, is the main driving shaft, which carries six wheels Cancer. connected by belts with the wheels on the as its true latitude, 24 deg. 5 min. 23 sec., does not saw shafts. In this they did'not make such a great error, The driving shaft is mounted so that it can be moved differ two-thirds of Ii degree from the true latitude of up and down, to loosen and tighten the belts. the Tropic of Cancer. This adjustment can be made from the main fioor. Figs. The saw blade is made up of a number of hinged cast-iron plates, which can be turned back for exami nation and adjustment of have direct lubrication. the saws. The bearings The resinous kert which the saws accumulate from pine wood is removed by fine jets of kerosene pumped from a five-gallon tank through 3 main and 34 branch tubes and occasionally thrown on both faces of all the saws, without stop ping the operation of the machine, by opening the 1 and 2. Using the Tropic of Cancer as a reference line, they the northern sky which we term the north celestial pole and which will remain unchanged in .its position to-night, although all the stars are apparently moving from east to west. H owever, they estimated it at 24 deg. There is no visible star occupying exactly this position, although the North Star approxi mates it. But this pole of the heav€ns is continually passing through a change in location. The terrestrial were able, by means of an instrument which may be termed a hollow gnomon, to determine latitudes north and south. This was a hemispherical shell having a rod directed radially from the lowest point of the inte rior of this cup-shaped piece of apparatus. terminated at the center of the sphere, This rod and quently was of the same length as a radius. on the day of the summer solstice, the conse At noon north pole cocks of the three main tubes that supply the three would-as we know-be directed toward the sun, as sets of saws. shown in Fig. 1. A line from the sun to the center of Each of the two sets of saws which are in line con the earth would pass through the Tropic of Cancer, O. tains 5 saws and cuts from the plank a :waste end or trimming and 4 pavJ.ng blocks. These two sets attack P, the hollow gnomon is fixed in such pOSition that the plank simultaneously. its central rod is vertical; If it be desired to determine the latitude of a point The middle portion of the that is, is continuation a plank passes on between them to the third set, which comprises 7 saws and divides the remnant into 8 equal of a radius of the earth. blocks. the center of �he shell, this arc is the measure of the the moment of noon. It is the arc P Q. The Hi blocks which are thus cut almost sim ultaneously from the plank continue to advance along of the conveyor and the table, pushed by the teeth angle Since T is As the sun, S, is very far away, the lines a. ST and S 0 0 are practically parallel. ,Consequen tly, come under held down by the springs L until they Its shadow is observed at the angles a and fJ are equal. The number of degrees, the . spring wheels M, where they remain until they are pushed onward by the following set of blocks. Thenceforward the blocks advance by steps, as they then, indicated by the arc P Q is the same as the num new to have been used by the Chinese as early as eleven ' are pushed onward by arrivals. the end of the table they slide reach When ber indicated by PO. But this latter arc represents the latitude of P from O. This instrument is supposed they down two in hundred clined planes,. divided into 16 compartments by verti cal partitions, to the three belts of a horizontal con years before Christ. Wh,ether or whether they invented it veyor, from which they are picked up and thrown into cars by a crew of 8 workmen. The cars, when filled, known. anew, is But they were not limited to this one instrument. The power which operates the saws is furnished by sun is immediately over the equator at the moment of noon. stalled in the basement and connected by two belts with this instrument was to be taken. This motor is controlled by on the main floor are two additional interrupters, an amperemeter, a voltmeter, and the controlling apparatus of a 4 horse power motor U, which supplies power to the convey ors. Finally, there is a traveling crane and windlass for the removal of the saws for resetting. The Josse machine can saw 25 planks per minute. As each plank furnishes 16 blocks, the theoretical out put of the machine in a are technically known as precession and nutation. near the close of the last century, certain astronomers began to suspect that not only was the 'axis of the earth continually relatively to changing its direction the stars, but 'that it was 'undergoing changes in the body of the earth itself. That is, they day of 10 hours is 25 x 16 x 60 o�oo +-o� 10 x 10 = 240,000 blocks. -0:/0 of pavi�g blocks can be turned out in a day with the D,'fO and fJ would be from the equator. Consequently, by determining the valne of a ,by means of the lengths of the indicator ' P T ,and the shadow P Q, we should arrive at the value sought. If one desires to satisfy himself how closely they indicated by a good atlas with the following latitudes as given by Hipparchus: Syracuse ................... 36 deg. 44 min. Byzantium (Constantinople).. 43 deg. Massilia (Marseilles)..... .... 43 deg. Ne_ National Forest In Arizona. It will be observed that the ancients were able to A new national forest, named the. Verde, and con use these methods only at certain particular mQments. sisting of 721,780 acres, has just been created in Mari In modern times, latitudes may be determined at any The forest lies on the wes t side of the Verde River and constitutes' a great part of its watershed. Jerome, where the United time of the year. ods. the pole of the heavens, E is a point on the equator. Consequently, NO is perpendicular to 0 E. If no great accuracy is west and southwest of Jerome are the Mingus Moun desired, the north star may be considered as the celes Most of the reserve is covered with brush that chantable timber on it and, under proper management, N is Fig. 3. To the has no commercial value; but a small part has mer Th( re are quite a number of meth But the followiug is qnite simple, and will be readily understood. Verde Copper Mining Company has its headquarters, is in the northern part of the new forest reserve. will supply the neighboring mining camps. a But fJ determines the latitude of P Athens ... .................. 36 deg. aid of 20 men or less. tains. a radius of the earth, the angles equal, as before. methods of modern science, let him compare the values -O:�O for unavoidable stoppages, etc., but a small mountain gnomon set up at P having its indicator in line with approximated to the values determined by the refined -d20 In practice it is necessary to make some allowance copa and Yavapai counties, Arizona. The line S 0, would pass through a point on the equator. With the motions which give rise to the movement of the pole But It is at such an instant that the observation Fig. 2, connecting t h e sun and t h e center of the earth; Fig. 3. a liquid rheostat W, with an amperemeter and a safety switchboard Upon the days of the vernal an� the autumnal equinoxes, the an electric motor U of 110 horse-power, which is in a not certainly' By this means, Eratosthenes determined the Another form of gnomon had a plane base. go to the storage yards. cut-off. Connected with Greeks latitude of Alexandria. are hauled over the Decauville railway tracks to the creosoting 'establishment, whence the creosoted blocks with the main shaft P'. the obtained their knowledge of it indirectly from them, 'l-O.£:O 0,00 +0.'10 Fig. The pro -O�/O tial pole. -O:cO instrument. The angle rp, is observed with a suitable That is to say, the elevation of the north star above the horizon is taken. 4. Now 0 P is perpen dicular to one side (P H) of rp, and 0 E is p erpendicu tection of the brush-grown area is just as important as that of heavily forested land, the scrub being the saw reasons to think that the geographical point on lar to the other side P N (P N being practically par only thing that the the earth called the north pole was shifting its posi allel to NO on account of the great distance of the The pro tion over the surface. This would mean, if true, that star). the latitude of New York city is not a fixed quantity. those of rp. conserves the water and watershed of the Verde River from erosion. saves tection of this watershed from damage by overgrazing That is, the sides of {} are This gives () = rp. perpendicular to But {} determines the and wasteful lumbering is necessary in the opinion The, reasons for entertaining suspicion in this matter latitude of P from E, the equator. So then, the eleva of the officers of the Reclamation Service to the de arose from the fact that variations of such number and tion of the north star above the velopment of the irrigable lands of Salt River Valley. character zon is exactly the same as the latitude of the place. came to light in redeterminations of the (astronomical) hori IENTIFI£ MERI£AN [Entered at the Post Office of New York, N. Y., as Second Class Matter. ' Copyright, 1908, by Mnnn & Co.] [ NEW YORK, APRIL 18, 1908. The Sawin)!: Table. 'fhe Horizontal Bed Has Been Lifted to Show the Arrangement of the Circular Saws. A MACHINE THAT SAWS 240,000 WOODEN PAVING BLOCKS IN A DAY.-[See page 273.] 10 CENTS A COPY $3.00 A YEAR.