三】
540
(4
(4)
The Committee are not in a position to say what salaries would be required at Hongkong for such officials, but, the "subordinate duties being such as intelligent non-commissioned officers of the army have been before "found competent to perform, they need not be very high.
"The Staff required would be a Superintendent, with two or three assistants.
"The Committee would therefore venture to hope that the Colonial Office will be pleased to "forward this suggestion to the proper quarter, with such recommendations on the subject as they are "led to anticipate from the interest in the promotion of Science so frequently evinced by your "Department, and which Governor POPE HENNESSY is so well qualified to appreciate."
Mr. BLANFORD, who is Meteorological Reporter to the Government of India, stated, in the letter above referred to,
"The results of the Meteorological system established by the Government of India have now "demonstrated the fact that the monsoons of India are distinct in origin and goal from those of the "China seas.
Each region is characterized by features peculiar to it, and we have now accumulated "a large amount of data relating to the Indian Monsoons which will receive a great extension so soon "as the nautical logs now in course of extraction and tabulation in the London Meteorological Office "shall be available for discussion. But, in the case of the China seas, our information is but little A first-class "advanced beyond the stage to which it was carried by Dové and Piddington.
observatory has indeed been established by the Jesuit Fathers at Shanghai, and another is now in course of equipment at Manila. But much more than this is required for the study of the China "Monsoons; and the proposed observatory at Hongkong will be a most valuable addition to the system."
Fü
64
wrote.
In his reply to the Secretary of State, dated 20th November, 1879, Governor POPE HENNESSY
"I have read with much interest Dr. WARREN DE LA RUE's letter enclosed in your despatch No. "105, of September last, suggesting on behalf of the Royal Society the establishment of an Observatory in this Colony, more especially with reference to Meteorology and Terrestrial Magnetism. As you were good enough to say that I might consider this question when bringing the Finances of the Colony before you, I have done so, and I venture earnestly to support Dr. DE LA RUE's suggestions, on local as well as on Imperial grounds.
"Two years ago, in the first Estimates I prepared in Hongkong, I took the liberty of including "a sum of $5,000 for an Observatory and Time Ball. Further consideration has convinced me that, "in addition to what may be necessary for securing an accurate Time Ball, we ought to have in this "Colony a thoroughly efficient means of recording such physical observations as Dr. De La Rue refers "to. Furthermore, the clearness of the atmosphere at certain seasons would admit of a valuable record being made of sun-spots. Incidentally, such questions as the tides and the varying temperature in "the seas surrounding Hongkong, the remarkable disintegration of the granite, which can be noticed almost from day to day in the island and in British Kowloon, and certain extremely slight, but not unfrequently occurring, earthquake phenomena, would probably be deserving also of the attention of competent observers.
"If, therefore, you will approve of my doing so, I shall be glad to submit to the Finance "Committee a vote of ten thousand dollars for a general scientific Observatory. I believe that such a vote would be cheerfully supported by the majority of the Legislative Council, and that there would "be no difficulty in including it in a supplementary Estimate for 1880.
It appears, therefore, that, in the proposal to establish this Observatory, three chief objects are aimed at, namely,
To determine the Local Time by astronomical observations, and drop a Time-Ball daily.
To obtain series of Meteorological observations with instruments of the best kinds, and to acquire information relating to the Typhoons and Monsoons of the China sea.
To obtain series of observations in Terrestrial Magnetism, also with the best modern apparatus.
I proceed to deal with these subjects, separately, in the above order.
( 5 )
I-Local Time.
The main purpose in dropping a Time-Ball is to enable the masters of the numerous sea-going vessels which come to Hongkong to ascertain the errors and rates of their standard time-keepers, without having recourse, as at present, to the practice of sending their chronometers ashore to be rated by the local watchmakers. Though this latter expedient is well known to be both clumsy and unsafe, yet, in ports not provided with a time-ball, it is practically the only one available to masters of merchant vessels, few of whom have the knowledge or leisure for the somewhat troublesome alternative of taking their own time-observations on shore with an artificial horizon and a hack chronometer. On the other hand, the errors and rates derivable from a time-ball accurately dropped are not only obtained with very little trouble, but are of vastly greater value than those which depend on any process that involves the movement of chronometers.
It follows that the Observatory determinations of time should be made and published with scientific precision, and be such as to command public confidence. They should supply the mariner with data in which, whether bound on a short run through the seas of these regions, or on a long ocean voyage, he may implicitly trust. In short, the working of the establishment ought to be made worthy of the grave interests involved, and of the requirements of one of the busiest shipping ports in the world.
In order to satisfy the above conditions, it will be necessary to provide the following instruments and apparatus --
(1). A Transit Instrument, of not less than three inches' clear aperture and about three feet focal length, constructed for fixing upon stone axis-piers, supplied with two setting-circles, and complete with the best modern fittings and auxiliary apparatus, spare webs, &c. The transit-threads in this instrument should be suited for chronographic observations. There is no necessity at present, in my opinion, to go to the expense of purchasing a transit-circle. Axis-piers, of Portland stone, may be furnished with the instrument.
(2). A Sidereal Standard Clock, geared to break an electrical circuit at every second, excepting one second in each minute and two consecutive seconds at every fifth minute.
(3). A Chronographic register, on Bond's principle, with a cylinder about twelve inches long and six or seven inches in diameter, driven by clock-work, and fitted for registering (1) sidereal seconds from the standard clock, (2) transit-signals from the observer at the instrument: and complete with all electrical and other apparatus and gear for these purposes, including a signal-key for the observer, glass scale for reading the record, and spare springs for the spring-governor.
(4). A Mean Solar Clock, fitted with contact-springs for discharging a time-ball automatically at a fixed instant by the clock each day. I recommend that this instant be made that of Local Mean Noon. Noon is a much more convenient time than one o'clock for ship-captains generally, and it is the hour to which all navigators refer their calculations. This clock should also be fitted with springs for sending a signal at ten o'clock daily. The necessity for such a signal is very likely to arise in the course of time.
The automatic dropping of a time-ball, or sending of a time-signal, on the arrival of the hands of a clock at a certain position necessitates the condition that the clock shall be right at that time. If it be not right, the time-ball or signal will obviously exhibit an error equal to that of the clock. The clock, therefore, must be fitted with apparatus by which minute errors, down to fractions of a second, may be corrected, and the clock set perfectly right beforehand. This can be effected by sending an electric current through a galvanic coil placed beneath the pendulum, which, by its action on a slender bar-magnet carried on the pendulum, imparts either an impulse or a check, according to the nature of the current sent through the coil, and thus accelerates or retards the stroke of the pendulum. This is done for such time (ascertainable by experiment) as may be needed in order to effect the required correction. A commutating apparatus serves for sending the proper current through the coil. Another method, the invention of Mr. SANG, C.E., consists of a mechanical arrangement by which the effective length of the pendulum may be diminished or increased by a minute amount, and the stroke thereby slightly quickened or retarded, for such interval as may be necessary in order to correct the error. One or the other of these contrivances should be fitted to the mean solar clock.
三】
540
(4
(4)
The Comittee are not in a position to say what salaries would be required at Hongkong for such officials, but, the "subordinate duties being such as intelligent non-commissioned officers of the army have been before "found competent to perform, they need not be very high.
"The Staff required would be a Superintendent, with two or three assistants.
"The Committee would therefore venture to hope that the Colonial Office will be pleased to "forward this suggestion to the proper quarter, with such recommendations on the subject as they are "led to anticipate from the interest in the promotion of Science so frequently evinced by your "Department, and which Governor POTE HENNESSY is so well qualified to appreciate."
Mr. BLANFORD, who is Meteorological Reporter to the Government of India, stated, in the letter above referred to,
"The results of the Meteorological system established by the Government of India have now "demonstrated the fact that the monsoons of India are distinct in origin and goal from those of the "China sens.
Each region is characterized by features peculiar to it, and we have now accumulated "a large amount of data relating to the Indian Monsoons which will receive a great extension so soon "as the nautical logs now in course of extraction and tabulation in the London Meteorological Office "shall be available for discussion. But, in the case of the China seas, our information is but little A first-class "advanced beyond the stage to which it was carried by Dové and Piddington.
observatory has indeed been established by the Jesuit, Fathers at Shanghai, and another is now in course of equipment at Manila. But much more than this is required for the study of the China "Monsoons; and the proposed observatory at Hongkong will be a most valuable addition to the
system."
Fü
64
wrote.
In his reply to the Secretary of State, dated 20th November, 1879, Governor POPE HENNESSY
"I have read with much interest Dr. WARREN DE LA RUE's letter enclosed in your despatch No. "105, of September last, suggesting on behalf of the Royal Society the establishment of an Observatory in this Colony, more especially with reference to Meteorology and Terrestrial Magnetism. As you were good enough to say that I might consider this question when bringing the Finances of the Colony before you, I have done so, and I venture earnestly to support Dr. DE LA RUE's suggestions, ou local as well as on Imperial grounds.
CL
"Two years ago, in the first Estimates I prepared in Hongkong, I took the liberty of including "a sum of $5,000 for an Observatory and Time Ball. Further consideration has convinced me that, "in addition to what may be necessary for securing an accurate Time Ball, we ought to have in this "Colony : a thoroughly efficient means of recording such physical observations as Dr. De La Rum refers "to. Furthermore, the clearness of the atmosphere at certain seasons would admit of a valuable record being made of sun-spots. Incidentally, such questions as the tides and the varying temperature in "the seas surrounding Hongkong, the remarkable disintegration of the granite, which cau be noticed almost from day to day in the island and in British Kowloon, and certain extremely slight, but not unfrequently occurring, earthquake phenomena, would probably be deserving also of the attention of competent observers.
(C
"If, therefore, you will approve of my doing so, I shall be glad to submit to the Finance "Committee a vote of ten thousand dollars for a general scientific Observatory. I believe that such a vote would be cheerfully supported by the majority of the Legislative Council, and that there would "be no difficulty in including it in a supplementary Estimate for 1880.
[C
It appears, therefore, that, in the proposal to establish this Observatory, three chief objects are aimed at, namely,
To determine the Local Time by astronomical observations, and drop a Time-Ball daily.
To obtain series of Meteorological observations with instruments of the best kinds, and to acquire information relating to the Typhoons and Monsoons of the China sea.
To obtain series of observations in Terrestrial Magnetism, also with the best modern apparatus.
I proceed to deal with these subjects, separately, in the above order.
( 5 )
I-Local Time.
The main purpose in dropping a Time-Ball is to enable the masters of the numerous sea-going vessels which come to Hongkong to ascertain the errors and rates of their standard time-keepers, without having recourse, as at present, to the practice of sending their chronometers ashore to be rated by the local watchmakers. Though this latter expedient is well known to be both clumsy and unsafe, yet, in ports not provided with a tine-ball, it is practically the only one available to masters of merchant vessels, few of whom have the knowledge or leisure for the somewhat troublesome alternative of taking their own time-observations on shore with an artificial horizon and a hack chronometer. On the other haud, the errors and rates derivable from a time-ball accurately dropped are not only obtained with very little trouble, but are of vastly greater value than those which depend on any process that involves the movement of chronometers.
It follows that the Observatory determinations of time should be made and published with scientific precision, and he such as to command public confidence. They should supply the mariner with date in which, whether bound on a short run through the seas of these regions, or on a long ocean voyage, he may implicitly trust. In short, the working of the establishment ought to be made worthy of the grave interests involved, and of the requirements of one of the busiest shipping ports in the world.
In order to satisfy the above conditions, it will be necessary to provide the following instruments and apparatus --
(1). A Transit Instrument, of not less than three inches' clear aperture and about three feet focal length, constructed for fixing upon stone axis-piers, supplied with two setting-circles, and complete with the best modern fittings and auxiliary apparatus, spare webs, &c. The transit-threads in this instrument should be suited for chronographic observations. There is no necessity at present, in my opinion, to go to the expense of purchasing a transit-circle. Axis-piers, of Portland stone, may be furnished with the instrument.
(2). A Sidereal Standard Clock, geared to break an electrical circuit at every second, excepting one
second in each minute and two consecutive seconds at every fifth minute.
(3). A Chronographic register, on Bend's principle, with a cylinder about twelve inches long and six or seven inches in diameter, driven by clock-work, and fitted for registering (1) sidereal seconds from the standard clock, (2) transit-signals from the observer at the instrument: and complete with all electrical and other apparatus and gear for these purposes, including a signal-key for the observer, glass scale for reading the record, and spare springs for the spring-governor.
4). A Mean Solar Clock, fitted with contact-springs for discharging a time-ball automatically at a fixed instant by the clock each day. I recommend that this instant be made that of Local Mean Noon. Noon is a much more convenient time than one o'clock for ship-captains ge- nerally, and it is the hour to which all navigators refer their calculations. This clock should also be fitted with springs for sending a signal at ten o'clock daily. The necessity for such a sigual is very likely to arise in the course of time.
The automatic dropping of a time-ball, or sending of a time-signal, on the arrival of the hands of a clock at a certain position necessitates the condition that the clock shall be right at that time. If it be not right, the time-ball or signal will obviously exhibit an error equal to that of the clock. The clock, therefore, must be fitted with apparatus by which minute errors, down to fractions of a second, may be corrected, and the clock set perfectly right beforehand. This can be effected by sending an electric current through a galvanic coil placed beneath the pendulum, which, by its action on a slender bar-magnet carried on the pendulum, impuris either an impulse or a check, according to the nature of the current sent through the coil, and thus accelerates or retards the stroke of the pendulum. This is done for such time (ascertainable by experiment) as may be needed in order to effect the required correction. A commutating apparatus serves for sending the proper current through the coil. Another method, the invention of Mr. SANG, C.E., consists of a mechanical arrangement by which the effective length of the pendulum may be diminished or increased by a minute amount, and the stroke thereby slightly quickened or retarded, for such interval as may be necessary in order to correct the error. One or the other of these contrivances should be fitted to the mean solar clock.
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