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Belting facts and figures
Belting Facts atid Pigures.
117
of the subject, we believe that we have been fair and just, and had the treatise under review appeared ten years since, we would ,have been less critical. As it is, nothing of any practical importance has been added to our stock of engineering literature, which we are sorry to say of any book. In these days of book-making it is pretty difficult for one to discriminate as to the best book on a given subject, so many have good titles, but only lead the beginner astray, either through incorrect deductions, or through a mode of treatment that makes an easy subject difficult. A. P:B.
BELTINGFACTS AND FIGURES, By J. H. COOPBE. (Continued
from page 29.)
Telodynamic Transmission.
FOR the following we are indebted to the interesting L‘Report on Machinery and Processes of the Industrial Arts,” by F. A. P. Bar. nard, LL.D., U. S. Commissioner to Paris Universal Faposition, 1867. We give only those parts which add new facts to the statements already made in an article on this subject. “The wheels are made as light as is consistent with strength, not only for the sake of reducing the inertia of the moving mass, and the friction on the axes to a minimum, but for the more important object of diminishing the resistance of the air. It can hardly be doubted that an abandonment of spokes entirely, and making the pulley a plain disc, would improve essentially the performance could discs be made at once strong enough to fulfill the required function and light enough not materially to increase the friction. It will be seen further on that the resistance of the air, which Mr. Hirn admits to be equal to the sum of the other resistances, is, in fact, more than double all the rest put together. ‘(This figure, which is a half size cross section of the rim c of the wheel, represents the form of the groove into which the &mature B of gutta-percha is compacted, and upon which the wire The dove-tail enlargement of this groove at the rope A rests. base is necessary, not merely to secure the gutta-percha against
118
Civil and ‘#&hanicaZ Eltgineering.
displacement by ordinary causes, but to prevent its being detached by centrifugal force. Mr. Hirn assumes 30 metres per second to be the velocity which it is expedient ordinarily to give to the circumference of the wheel ; but he has carried this occasionally as high as 40 metres. At 30 metres the centrifugal force generated at the circumference of the smaller pulleys of 2 metres in diameter, will be between 90 and 100 times the force of gravity, and at 40 it will be nearly 170 times gravity. That is to say, as the circumference of such a wheel measures a little over 20 feet around, if each foot of this circumference weighs one pound, the whole will be dragged in all directions with this last velocity by forces which unitedly will amount to nearly 18 tons. It is on this account that Mr. Hirn suggests that the limit of 30 metres, had better not be overpassed, higher velocities endangering the destruction of the wheel. ‘LThe invention of Mr. Hirn was first applied in the transmission of moderate powers to moderate distances.” “Instead of a cable there was used in the beginning a band of steel, having a breadth of about 24 inches, and a thickness of &th In the first place of an inch. This presented two inconveniences. on account of its considerable surface, it was liable to be agitated by the winds; and, secondly, it soon became worn and injured at the points where it was riveted. “It served, however, very well for eighteen months to transmit 12 horse-power to a distance of 80 metres. “A cable was then substituted, and this first introduced in 1852, is still in good condition. “ The applications have been made for the most part in France, and in the department in which the invention originated, but there are some notable exceptions.” “ In the great government manufactory of gunpowder at Okhta in Russia, which was destroyed in 1864 by explosion, it was determined in the reconstruction of the works to erect the buildings at such a distance from each other that the explosion of one of them should not involve, as happens usually in such cases, the ruin of all the rest. ‘This new manufactory which went into operation in 1867 is cornposed of thirty-four different workshops or laboratories, to which motive power is transmitted from three turbines, having a total force of 274 horsedpower along a line nearly a mile in length.
Belling Facts and Figures.
119
Several establishments in Germany employ it for distances varying from 350 to 1,200 metres. An officer of the Danish Navy has made one application of it on a line of 1,000 metres, and at the mines of Falun, in Sweden, more than 100 horse-power is transmitted by it to a distance of 5,000 metres. “ The cost of the machinery and its erection is estimated at 5,000 francs per kilometre, exclusive of the necessary constructions at the termini, which will require an additional expenditure of 25 francs per horse-power. In the case of 100 horse-power carried 10 kilometres, the total expense will therefore amount to 52,500 francs. (‘For its practical value, this invention, simple as it appears, is one of the most important that has presented itself in the Exposition, and the jury have shown that they so regard it, by awarding to the inventor the distinction of a grand prize.” (To be continued.)
Suez Canal,-The latest information published by the O$;ciul Journal of the canal gives the following among other information. It quotes two telegrams, in the first instance, one dated Ismailia, December 27, the other Port Said, December 30. The first runs thus :-“ The steamer Stirling, from Glasgow, of 800 tons, arrived at Port Said, and proceeded direct for Bombay, the voyage through the canal having been performed in less than sixteen hours. Upwards of 50 steamers are lading in different ports of Europe which will pass through the canal.” The second telegram states that the engineers report that the state of the canal banks presents no perceptible change since the inauguration. The French steamer Malta, and the English steamer Rocket, on her way to Shanghai, have passed the canal. At Serapeum, where the canal was too shallow, it has been deepened to 194 feet, and there remained only 2 metres to complete the whole length of the canal, out of about 80 metres. To gratify the impatience of the shareholders the names of some of the largest of the vessels that have passed, or will pass, are pubthe head of these are English veslished, and are as follows :-At sels : the Brazilian, of 2,815 tons register ; the Queen of the South, 2,097 tons; the Mauritius, 2,150 tons ; the Port Said, 898 tons; the Ismailia, 899 tons; and the Bolivian, 2,815 tons. The vessels belonging to the Ocean Steamship Company are to pass regularly through the canal.
117
of the subject, we believe that we have been fair and just, and had the treatise under review appeared ten years since, we would ,have been less critical. As it is, nothing of any practical importance has been added to our stock of engineering literature, which we are sorry to say of any book. In these days of book-making it is pretty difficult for one to discriminate as to the best book on a given subject, so many have good titles, but only lead the beginner astray, either through incorrect deductions, or through a mode of treatment that makes an easy subject difficult. A. P:B.
BELTINGFACTS AND FIGURES, By J. H. COOPBE. (Continued
from page 29.)
Telodynamic Transmission.
FOR the following we are indebted to the interesting L‘Report on Machinery and Processes of the Industrial Arts,” by F. A. P. Bar. nard, LL.D., U. S. Commissioner to Paris Universal Faposition, 1867. We give only those parts which add new facts to the statements already made in an article on this subject. “The wheels are made as light as is consistent with strength, not only for the sake of reducing the inertia of the moving mass, and the friction on the axes to a minimum, but for the more important object of diminishing the resistance of the air. It can hardly be doubted that an abandonment of spokes entirely, and making the pulley a plain disc, would improve essentially the performance could discs be made at once strong enough to fulfill the required function and light enough not materially to increase the friction. It will be seen further on that the resistance of the air, which Mr. Hirn admits to be equal to the sum of the other resistances, is, in fact, more than double all the rest put together. ‘(This figure, which is a half size cross section of the rim c of the wheel, represents the form of the groove into which the &mature B of gutta-percha is compacted, and upon which the wire The dove-tail enlargement of this groove at the rope A rests. base is necessary, not merely to secure the gutta-percha against
118
Civil and ‘#&hanicaZ Eltgineering.
displacement by ordinary causes, but to prevent its being detached by centrifugal force. Mr. Hirn assumes 30 metres per second to be the velocity which it is expedient ordinarily to give to the circumference of the wheel ; but he has carried this occasionally as high as 40 metres. At 30 metres the centrifugal force generated at the circumference of the smaller pulleys of 2 metres in diameter, will be between 90 and 100 times the force of gravity, and at 40 it will be nearly 170 times gravity. That is to say, as the circumference of such a wheel measures a little over 20 feet around, if each foot of this circumference weighs one pound, the whole will be dragged in all directions with this last velocity by forces which unitedly will amount to nearly 18 tons. It is on this account that Mr. Hirn suggests that the limit of 30 metres, had better not be overpassed, higher velocities endangering the destruction of the wheel. ‘LThe invention of Mr. Hirn was first applied in the transmission of moderate powers to moderate distances.” “Instead of a cable there was used in the beginning a band of steel, having a breadth of about 24 inches, and a thickness of &th In the first place of an inch. This presented two inconveniences. on account of its considerable surface, it was liable to be agitated by the winds; and, secondly, it soon became worn and injured at the points where it was riveted. “It served, however, very well for eighteen months to transmit 12 horse-power to a distance of 80 metres. “A cable was then substituted, and this first introduced in 1852, is still in good condition. “ The applications have been made for the most part in France, and in the department in which the invention originated, but there are some notable exceptions.” “ In the great government manufactory of gunpowder at Okhta in Russia, which was destroyed in 1864 by explosion, it was determined in the reconstruction of the works to erect the buildings at such a distance from each other that the explosion of one of them should not involve, as happens usually in such cases, the ruin of all the rest. ‘This new manufactory which went into operation in 1867 is cornposed of thirty-four different workshops or laboratories, to which motive power is transmitted from three turbines, having a total force of 274 horsedpower along a line nearly a mile in length.
Belling Facts and Figures.
119
Several establishments in Germany employ it for distances varying from 350 to 1,200 metres. An officer of the Danish Navy has made one application of it on a line of 1,000 metres, and at the mines of Falun, in Sweden, more than 100 horse-power is transmitted by it to a distance of 5,000 metres. “ The cost of the machinery and its erection is estimated at 5,000 francs per kilometre, exclusive of the necessary constructions at the termini, which will require an additional expenditure of 25 francs per horse-power. In the case of 100 horse-power carried 10 kilometres, the total expense will therefore amount to 52,500 francs. (‘For its practical value, this invention, simple as it appears, is one of the most important that has presented itself in the Exposition, and the jury have shown that they so regard it, by awarding to the inventor the distinction of a grand prize.” (To be continued.)
Suez Canal,-The latest information published by the O$;ciul Journal of the canal gives the following among other information. It quotes two telegrams, in the first instance, one dated Ismailia, December 27, the other Port Said, December 30. The first runs thus :-“ The steamer Stirling, from Glasgow, of 800 tons, arrived at Port Said, and proceeded direct for Bombay, the voyage through the canal having been performed in less than sixteen hours. Upwards of 50 steamers are lading in different ports of Europe which will pass through the canal.” The second telegram states that the engineers report that the state of the canal banks presents no perceptible change since the inauguration. The French steamer Malta, and the English steamer Rocket, on her way to Shanghai, have passed the canal. At Serapeum, where the canal was too shallow, it has been deepened to 194 feet, and there remained only 2 metres to complete the whole length of the canal, out of about 80 metres. To gratify the impatience of the shareholders the names of some of the largest of the vessels that have passed, or will pass, are pubthe head of these are English veslished, and are as follows :-At sels : the Brazilian, of 2,815 tons register ; the Queen of the South, 2,097 tons; the Mauritius, 2,150 tons ; the Port Said, 898 tons; the Ismailia, 899 tons; and the Bolivian, 2,815 tons. The vessels belonging to the Ocean Steamship Company are to pass regularly through the canal.