scholarly journals Experiments to determine the difference the number of vibrations made by an invariable pendulum in the royal observatory at Greenwich, and in the house in London in which Captain Kater’s experiments were made

1833 ◽  
Vol 2 ◽  
pp. 360-360
Keyword(s):  
Royal Society ◽  
Royal Observatory ◽  
The Mean ◽  
The Difference ◽  
The Times ◽  
Theory And Experiment ◽  
Made In

The experiments of which an account is given in this paper, were made in compliance with a request of the Council of the Royal Society, made in December 1827, that Captain Sabine would ascertain the difference in the number of vibrations of a pendulum at Mr. Browne’s house, and at the Greenwich Observatory. The author gives a description of the instruments used in the observations; the first series of which were made in Mr. Browne’s house, from the 17th to the 20th of March inclusive, and gave as the mean result, 85963·60 vibrations in a mean solar day. A reduction is here introduced, derived from some experiments made on the difference which takes place in the times of vibration in vacuo and in air; the number of vibrations in the former case being, under the same circumstances as in the observations, 9·97 per diem less than in the latter. A corresponding series made at Greenwich in May, gave as the mean 85964·17 vibrations, thus indicating an acceleration of 0·57 vibrations per diem , but the difference of latitude and of height between the two stations would have led us from theory to expect a total retardation of 0·38 vibration in the same time. From a second set of observations at Greenwich, the diurnal acceleration appeared to be 0·52 vibration. Taking the mean of this and the former result, it appears that the total amount of the discordance between theory and experiment is 0·91 vibration per diem . The stations are conveniently situated for verifying the existence of this anomaly, and its magnitude is such as to preclude all uncertainty as to its existence. With regard to its cause, the author is confirmed in the opinions he formerly entertained on this subject. Tables are subjoined, containing accounts of the rate of the clocks used at both stations, and of the particulars of each series of observations.

scholarly journals XXXIV. Observations on the transit of Ve­nus, June the 6th, 1761, made in Spital-Square; the longitude of which is 4' 11" west of the Royal Observatory at Green­wich, and the latitude 51° 31' 15" north

1761 ◽  
Vol 52 ◽  
pp. 182-183
Keyword(s):  
The Sun ◽  
Royal Observatory ◽  
The Mean ◽  
The Difference ◽  
Made In

Having measured the diameter of Venus, on the sun, three times, with the object-glass micrometer, the mean was found to be 58 seconds; and but 6/10 of a second, the difference of the extremes.

scholarly journals IX. Experiments to determine the difference in the number of vibrations made by an invariable pendulum in the Royal Observatory at Greenwich, and in the house in London in which Captain Kater’s experiments were made

1829 ◽  
Vol 119 ◽  
pp. 83-102 ◽  
Keyword(s):  
Royal Society ◽  
Knife Edge ◽  
Capillary Action ◽  
Royal Observatory ◽  
The Difference ◽  
Made In

These experiments were made in compliance with a wish of the Council of the Royal Society, expressed in the following minute, dated December 13th 1827: “That Captain Sabine be requested to ascertain the difference in the number of vibrations of a pendulum between Mr. Browne’s house in London and the Royal Observatory at Greenwich.” The invariable pendulum employed to accomplish the proposed object was of the usual materials and form, new for the occasion, and numbered 12. The thermometer was the same that I had used in my former pendulum experi­ments; its graduation is described in the volume containing the account of those experiments, pages 182—187. The ball of the thermometer was sus­pended at both stations midway between the knife edge and the centre of the weight of the pendulum. The height of the barometer in the observations at Greenwich was taken by the standard barometer of the Observatory, which is in a room on the same floor as the pendulum room: in those at London it was taken by Mr. Browne’s barometer placed in the room in which the observa­tions were made. Mr. Browne’s barometer being compared with the standard of the Greenwich observatory, by means of an intermediate portable barometer, was found to require a correction of + 0.066 to make it agree with the indications of the Greenwich standard corrected for capillary action. This correction is consequently applied.

Hourly observations on the barometer, with experimental investigations into the phenomena of its periodical oscillation

1837 ◽  
Vol 3 ◽  
pp. 136-137
Keyword(s):  
Royal Society ◽  
Daily Variation ◽  
Experimental Investigations ◽  
Great Length ◽  
Linear Representations ◽  
The Mean ◽  
Meteorological Observations ◽  
The Times ◽  
Straight Lines ◽  
Made In

Mr. Lubbock having found, from his examination of the meteorological observations made daily at the Royal Society, that they afforded no satisfactory result as to the daily variation o f the barometer in consequence of the too great length of the intervals between the times of observation, the author undertook the task of making a series of hourly observations for a period sufficiently extensive to furnish preliminary data for explaining the anomalies of the barometrical oscillations. The present paper contains these hourly observations, amounting to about 3000 in number, and made in the months of April, May, June, and July, 1831, and in those of January and February of 1832. The standard barometer of the Society has been observed for about 16 or 18 hours during the day, through a period of 75 days; and also at every hour, through the whole twenty-four hours, for 30 days: the water barometer every hour, day and night, for 15 days; and the mountain barometer also every hour, day and night, for the same period. The relative levels of the surfaces of the fluids in the cisterns of each of these barometers, were accurately determined by Mr. Bevan. The most striking results afforded by these observations are exhibited by means of linear representations in four drawings which accompany the paper. The respective variations from each general mean, being referred, according to a given scale, to the mean line, and their points of distance from it, at each successive hour, being connected together by straight lines, the barometrical and thermometrical changes being each referred to the same scale, exhibits the striking connexion that exists between them. The comparison of the simultaneous movements of the three barometers shows the general accordance of their mean variations; and the precession in time, by about an hour, of the mean motions of the water barometer over those of the standard barometer; and also the precession, by the same interval, of the mean changes of this latter instrument over those of the mountain barometer. The author concludes by announcing many objects he has in view in the investigations in which he is at present engaged.

scholarly journals XIX. On the difference of meridians of the Royal Observatories of Greenwich and Paris

1827 ◽  
Vol 117 ◽  
pp. 286-296 ◽  
Keyword(s):  
The Other ◽  
Detailed Account ◽  
Sidereal Time ◽  
Methods Of Calculation ◽  
Royal Observatory ◽  
The Difference ◽  
Made In

In the Philosophical Transactions for 1826, Part II. Mr. Herschel has given a detailed account of observations, which were made in the month of July, 1825, for the purpose of ascertaining the difference of the meridians of the Royal Observatories of Greenwich and Paris, with a computation of these observations, from which the most probable value of the difference of longitude appears to be 9 m 21 s. 6. But I have perceived that in the copy of the observations delivered to him from the Royal Observatory of Greenwich, an error of one second has been committed; as the true sidereal time of the observation made there on 21st July, ought to be 17 h 38 m 57·12 in place of 17 h 38 m 56 s. 10, set down in the Table p. 104, which he informs me was computed at the Observatory, and officially communicated to him from the Astronomer Royal. This error seems to have had its origin in the little Table at the bottom of page 103; for, on subtracting the error of the clock, 47 s. 37, from the time 18 h 8 m 30 s. 40, the true sidereal time is 18 h 7 m 43 s. 03, instead of 18 h 7 m 42 s. 03, there given. The error in the result of that day’s observations, arising from this cause, has been partly compensated by a mistake of three tenths of a second, which has occurred in calculating the combined observations of the same day, the gain of mean on sidereal time being stated to be — 4 s. 54 (pp. 120 and 122), in place of — 4 s. 24. On checking the other observations, a few trifling alterations appear to be necessary upon the Greenwich Table of sidereal time, from the data given along with it. These seem to be occasioned by different methods of calculation, and indeed are hardly worthy of notice. The French astronomers not having given the data on which the calculations of the sidereal times at Paris are founded, they are assumed to be correct.

XII. The Bakerian Lecture.—On a method of meteorological registration of the chemical action of total daylight

1865 ◽  
Vol 155 ◽  
pp. 605-631 ◽  
Keyword(s):  
Royal Society ◽  
Short Length ◽  
Direct Sunlight ◽  
Arbitrary Degree ◽  
Chemical Action ◽  
Reflected Light ◽  
Standard Paper ◽  
Calm Weather ◽  
The Times ◽  
Made In

In the last memoir on Photochemical Measurements, presented to the Royal Society, Professor Bunsen and I described a method for determining, by simple observations, the varying amount of chemical action effected by the direct and diffuse sunlight on photographic paper, founded upon a law discovered by us, viz. that equal products of the intensity of the light into the times of insolation correspond within very wide limits to equal shades of tints produced on chloride-of-silver paper of uniform sensitiveness—so that light of the intensity 50, acting for the time 1, produces the same blackening effect as light of the intensity 1 acting for the time 50. For the purpose of exposing this paper to light for a known but very short length of time, a pendulum photometer was constructed; and by means of this instrument a strip of paper is so exposed that the different times of insolation for all points along the length of the strip can be calculated to within small fractions of a second, when the duration and amplitude of vibration of the pendulum are known. The strip of sensitive paper insolated during the oscillation of the pendulum exhibits throughout its length a regularly diminishing shade from dark to white; and by reference to a Table, the time needed to produce any one of these shades can be ascertained. The unit of photo-chemical intensity is assumed to be that of the light which produces upon the standard paper in the unit of time (one second) a given but arbitrary degree of shade termed the normal tint. The reciprocals of the times during which the points on the strip have to be exposed in order to attain the normal tint, give the intensities of the acting light expressed in terms of the above unit. According to this method the chemical action of the total daylight ( i. e . the direct sunlight and the reflected light from the whole heavens) has been determined, by means of observations made at frequent intervals throughout the day, and curves representing the variation of daily chemical intensity at Manchester have been drawn. The labour of obtaining a regular series of such daily measurements of the chemical action of daylight according to this method is, however, very considerable; the apparatus required is bulky, the observations can only be made in calm weather, and the quantity of sensitive paper needed for a day’s observations is large.

scholarly journals XIII. Results deduced from the measures of terrestrial magnetic force in the horizontal plane, at the Royal Observatoy, Greenwich, from 1841 to 1876

1885 ◽  
Vol 176 ◽  
pp. 679-689
Keyword(s):  
Royal Society ◽  
Horizontal Plane ◽  
Magnetic Force ◽  
Proper Part ◽  
Royal Navy ◽  
Sliding Windows ◽  
Short Statement ◽  
Royal Observatory ◽  
Real Progress ◽  
Made In

In offering to the Royal Society some results deduced from the systems of magnetic observation and magnetic self-registration established several years since at the Royal Observatory, Greenwich, during a portion of the time in which I presided over that institution, I think it desirable to premise a short statement on the origin of the Magnetic Department of the Royal Observatory, and on the successive steps in its constitution. It appears to have been recognised many years ago, that magnetic determinations would form a proper part of the business of the Royal Observatory. When I commenced residence at the Royal Observatory, at the end of 1835, I found in the garden a small wooden building, evidently intended for the examination of compasses, perhaps of the size of those used in the Royal Navy. But the locality was inconvenient, and the structure was totally unfit for any delicate magnetic purpose; for instance, the balance-weights of the sliding windows were of iron. For some preliminary experiments a small observatory was borrowed from Captain Fitzroy, but no real progress was made in magnetism.

scholarly journals X. An account of operations carried on for ascertaining the difference of level between the River Thames at London Bridge and the sea; and also for determining the height above the level of the sea, &c. of intermediate points passed over between Sheerness and London Bridge

1831 ◽  
Vol 121 ◽  
pp. 167-197 ◽  
Keyword(s):  
Royal Society ◽  
The Mean ◽  
River Thames ◽  
The Difference ◽  
To Receive

In February 1830, at the suggestion of the Royal Society, I had the honour to receive directions from the Lords Commissioners of the Admiralty to make such observations as I might consider necessary, to ascertain the difference, if any, between the level of the waters at certain points on the river Thames, and the mean level of the sea near Sheerness, as well as the height of different intermediate points above the sea, such as Gravesend, Greenwich Observatory, &c. Having found, while employed in the Isthmus of Darien, how inadequate the present levelling instruments were to obtain very accurate results, and being desirous of conducting the interesting observations, I now had orders to make, with the most scrupulous exactness, I thought it necessary, in the first instance, to bestow some attention to the improvement of the instruments required to be used, endeavouring to combine superior steadiness and motion in azimuth, more delicacy in the level itself, more permanency in its position, and greater power in the telescope.

VIII. On the corrections to be applied to the monthly means of meteorological observations taken at any hour, to convert them into mean monthly values

1848 ◽  
Vol 138 ◽  
pp. 125-139 ◽  
Keyword(s):  
Monthly Means ◽  
Mean Values ◽  
Short Intervals ◽  
Perfect Knowledge ◽  
Royal Observatory ◽  
The Mean ◽  
The Difference ◽  
Meteorological Observations ◽  
Essential Service

One of the most useful results of observations made at short intervals during the day and night, and continued for several years, is the knowledge we thus obtain of the diurnal ranges of the different subjects of investigation, and consequently the difference between the mean values of each element, as deduced from observations at one or more hours daily, and the true mean for the period over which the observations are spread. At the Royal Observatory at Greenwich magnetical and meteorological observations have been taken since the year 1840, as is familiar to the Fellows of this Society. These have been published to the end of the year 1845. The whole of these observations have been made under my immediate superintendence, under the direction of the Astronomer Royal, and I believe that no observations have been made and reduced with greater care or regularity. As the person entrusted with the superintendence of these operations, I have a more perfect knowledge of them than any other person can have; I feel it therefore a duty to communicate their results from time to time, when the doing so promises to be of essential service in promoting the advancement of the subjects of investigation.

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