F 13
The Dent mean time clock, No. 39740, which was sent to Messrs. E. Dent & Co., London, in June, 1914, to be fitted with an invar pendulum, with hardened lead bob, and electric contacts for emitting 2-second signals, was received back on February 16, and set up the following day. The clock has not yet settled down to a steady rate, and no pressure or humidity co-efficients can be determined from the rates obtained up to the present. It would appear, however, that an increase of 1° F. of temperature increases the daily gaining rate by 0.039. When examined at the National Physical Laboratory, London, the mean co-efficient of linear dilatation of the pendulum rod was found to be nil between the temperatures 32° and 86° Fahrenheit.
The Brock clock has been used for dropping the time ball throughout the year and for driving dials in various parts of the building. It has worked without failure, and the electric contacts have required no adjustment. The rate has been erratic at times, however, in spite of the invar pendulum fitted in 1914. The clock is corrected daily by the electric regulating apparatus, and its daily rate is usually kept within 0.5 by the addition or removal of weights from the pendulum.
The rate of chronometer Kullberg No. 8546 has improved somewhat, but has not settled down to the excellent rate reported in 1913.
The only failures with the electric impulse dials have been those due to exhausted primary batteries. The motive power is now derived from the accumulator and no further trouble is anticipated.
The pallet of the electric standard clock was jewelled, the bearings of the gravity roller improved, and the effective weight of the gravity arm reduced, free of charge, by Messrs. Gent & Co., and fresh experiments are being made to determine the best working values of impulse, arc, and friction, under the new conditions.
Accumulators.-The installation of an accumulator battery of ten three-plate Tudor cells of 27 ampère-hour capacity and 9 ampères maximum discharge, which was commenced by the Public Works Department in the month of November, 1913, was delayed on account of the illness of the Government Electrician, and ultimately placed in the hands of the China and Japan Telephone Company. The cells were remounted and a Nodon valve, consisting of four iron jars with aluminium electrodes, substituted for the valve originally supplied, which was found to be unsatisfactory. The new valve also gave considerable trouble owing to the inferior quality of the ammonium phosphate, and possibly to other causes.
The valve was cleaned on November 25, and a new solution of ammonium phosphate, recently received from England, substituted for the old solution in which was found a very heavy deposit. The valve has since worked well, but considerable crystallization takes place, and a fan is necessary to prevent undue heating.
F 13
The Dent mean time clock, No. 39740, which was sent to Messrs. E. Dent & Co., London, in June, 1914, to be fitted with an invar pendulum, with hardened lead bob, and electric contacts for emitting 2-second signals, was received back on February 16, and set up the following day. The clock has not yet settled down to a steady rate, and no pressure or humidity co-efficients can be deter- mined from the rates obtained up to the present. It would appear, however, that an increase of 1° F. of temperature increases the daily gaining rate by 0039. When examined at the National Physical Laboratory, London, the mean co-efficient of linear dilatation of the pendulum rod was found to be nil between the temperatures 32° and 86° Fahrenheit.
The Brock clock has been used for dropping the time ball throughout the year and for driving dials in various parts of the building. It has worked without failure, and the electric contacts have required no adjustment. The rate has been erratic at times, however, in spite of the invar pendulum fitted in 1914. The clock is corrected daily by the electric regulating apparatus, and its daily rate is usually kept within 05 by the addition or removal of weights from the pendulum.
The rate of chronometer Kullberg No. 8546 has improved somewhat, but has not settled down to the excellent rate reported in 1913.
The only failures with the electric impulse dials have been those due to exhausted primary batteries. The motive power is now derived from the accumulator and no further trouble is anticipated.
The pallet of the electric standard clock was jewelled, the bearings of the gravity roller improved, and the effective weight of the gravity arm reduced, free of charge, by Messrs. Gent & Co., and fresh experiments are being made to determine the best working values of impulse, arc, and friction, under the new conditions.
Accumulators.-The installation of an accumulator battery of ten three-plate Tudor cells of 27 ampère-hour capacity and 9 ampères maximum discharge, which was commenced by the Public Works Department in the month of November, 1913, was delayed on account of the illness of the Government Electrician, and ultimately placed in the hands of the China and Japan Telephone Company. The cells were remounted and a Nodon valve, consisting of four iron jars with aluminium electrodes, substituted for the valve originally supplied, which was found to be unsatisfactory. The new valve also gave considerable trouble owing to the inferior quality of the ammonium phosphate, and possibly to other causes.
The
The valve was cleaned on November 25, and a new solution of ammonium phosphate, recently received from England, substituted for the old solution in which was found a very heavy deposit. valve has since worked well, but considerable crystalization takes place, and a fan is necessary to prevent undue heating.
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