Amounts of Rain collected in Four Gauges Relations of the Amounts of Rain which fell under different Winds in 1862 DIURNAL INEQUALITIES OF MEAN MONTHLY METEOROLOGICAL ELEMENTS ; CHANGES AND INFLUENCE OF THE WIND; QUANTITY OF RAIN, &c., &c. [33] TABLE I.-Mean Monthly Heights of the Barometer for every Two Hours. TABLE II. -Values of the Constants in the Periodical Expression for the Mean Monthly Diurnal Inequalities of Barographic Results TABLE III.-Excess of the Mean Monthly Result of the Barograph at each TABLE IV.-Mean Monthly Temperatures of the Air for every Two Hours TABLE V.-Values of the Constants in the Periodical Expression for the Mean Monthly Diurnal Inequalities of Thermographic Results TABLE VI.-Excess of the Mean Monthly Temperature of the Air at each TABLE VIII.-Values of the Constants in the Periodical Expression for the Mean Monthly Diurnal Inequalities of the Hygrographic Results TABLE IX.-Excess of the Mean Monthly Temperature of Evaporation at each Hour above the Mean Monthly Temperature for the Day TABLE X.-Mean Monthly Elasticity of Vapour for every Two Hours of Formula for the Mean Yearly Elasticity of Vapour at any Hour TABLE XI.-Mean Monthly Pressures of Dry Air for every Two Hours TABLE XV.-The Principal Changes of Wind during the Year 1862 TABLE XVI.-Relations of Pressure, Temperature, &c., under different INTRODUCTION TO THE ASTRONOMICAL OBSERVATIONS OF 1862. SECTION I.-Personal Establishment and Instruments. PERSONAL ESTABLISHMENT.-The Establishment of Assistants of the Observatory during the year 1862 was precisely the same as that which existed in the latter portion of the preceding year. The first Assistant was, as before, Mr. Adolphus Quirling, and the second Assistant Mr. John Lucas. Mr. William Luff was, as before, computer to the Establishment, and was occupied mainly with the reduction of the observations of zenith-distance made with the Transit Circle. Mr. Lucas took charge, as in the preceding year, of the Photographic Meteorology, as is more particularly mentioned in the Introduction to the Meteorological Observations. The greater portion of the Transit Observations made with the Transit Circle were reduced by Mr. Quirling. INSTRUMENTS.—A great organic change was made in the year 1862 by the discontinuance of the use of the Transit Instrument and Meridian Circle formerly employed, and the substitution of the Carrington Transit Circle. This Instrument was purchased of Mr. Carrington; transferred, with the stones of its piers, to Oxford; and remounted in the west Transit Room of the Radcliffe Observatory during the preceding year; (as is stated at pages i and ii of the Introduction to the Astronomical Observations of 1861,) and was in use for ordinary observations from the commencement of the year 1862. At the close of this Section of the Introduction a more detailed statement will be given concerning it and its mode of use. The stars observed with the Transit Circle are taken from a compiled list extracted from the British Association Catalogue, including RADCLIFFE OBSERVATIONS, 1862. b all below the fifth magnitude to the seventh inclusive which have not been observed satisfactorily at Greenwich or Oxford. The sun, the moon, and the large planets have been observed within the limits of the observing hours-which extend to midnight during the winter months, and to 13h M. T. during the summer months. The observations with the Transit Circle were made generally by Mr. Quirling and Mr. Lucas on alternate nights. Their initials, which are given in the Separate Results of the Stars in N. P. D., are Q and L. No other change of instruments was made in the year 1862. The Heliometer was, as before, used by myself for observations of double stars and the diameters of large planets, great attention being paid in particular to the planet Mars. The double stars observed in this and the preceding year were selected from Smyth's Cycle of Celestial Objects. A series of observations of the Great Comet of 1862 was also made with the Heliometer, and some occultations of stars by the moon were observed with it. A full description of the instrument will be found in the eleventh and fourteenth volumes of the Radcliffe Observations. The Transit Instrument.-This instrument was in use till the end of the year 1861, when it was replaced by the Transit Circle. It was removed, as before stated, from the west to the east Transit Room in September 1861. It is kept in good condition, and is available for any purpose for which it may be required, but especially for practice of students of the University. A description of it will be found in vols. I and IV of the Radcliffe Observations. The Meridian Circle.-This instrument was also thrown out of use at the end of 1861, and is also available for purposes of instruction. It is fully described in vol. I of the Radcliffe Observations. Other instruments belonging to the Observatory are, 1st, a telescope of 10 feet focal length, and 7 inches aperture, mounted equatorially on the south front of the Observatory, and used in connexion with a journeyman clock, striking at the termination of each minute; and a 42-inch achromatic telescope, with triple object-glass of 3 inches. Observations and discoveries made with the 10-foot telescope in preceding years by Mr. Pogson have occasionally appeared in the Astronomische Nachrichten and in the Monthly Notices of the Royal Astronomical Society. The ancient instruments out of use consist of two brass 8-foot Quadrants by Bird, and a 12-foot zenith-sector, in connexion with which may be mentioned an old Barometer by Bird. There is also a 10-foot Newtonian telescope by Sir W. Herschel. The principal clocks belonging to the Observatory are four in number: namely, two with mercurial compensation pendulums, by Dent, used with the Transit Circle and the Heliometer; and two with gridiron pendulums, the first of which, by Shelton, is in the apartment of the Meridian Circle, and the second, by Hawting, in the east Transit Room. The three first mentioned are excellent instruments; the last is an old clock (still useful), but of an inferior character. There is also a clock with wooden pendulum, which stands in the central hall, and serves to give time for the regulation of ordinary business. A pocket Chronometer by Hardy, adjusted to mean solar time, is used for comparison of clocks and for occasional observations. The Barometer used with the Transit Circle is by Newman, and has a fiducial point, which is brought into contact with the surface of the mercury; that used formerly with the Heliometer is by Jones, and has a bag and float for the adjustment of the level of the cistern. The latter was, in the year 1862, placed in the Transit Circle Room, near that by Newman in actual use. Description, Adjustments, and Mode of Use of the Transit Circle.It has been previously mentioned that this instrument was purchased of Mr. Carrington and conveyed to Oxford in the summer of 1861, and that in September of that year I prepared to mount it on its former piers in the west Transit Room of the Observatory, having previously removed the Transit Instrument for use to the east Transit Room. On stripping the flooring, as far as was necessary, it was found that very little addition was necessary to the foundation which previously existed. The foundation-piers of the Transit Instrument to the level of the flooring were adapted to the new instrument, by simply building up small square brick columns at the corners; and a very solid brick wall, which was found to run north and south in the plane of the meridian, was admirably adapted, without any alteration, to sustain the piers of the north and south collimators. The dimensions of the two piers of the instrument at the level of the flooring are 5 feet by 2 feet 5 inches; and those of the piers of the collimators are 3 feet by 1 foot 10 inches. The extreme height of the piers of the instrument is 7 feet 9 inches, and the space between them is 2 feet 6 inches. The height of the centre of the telescope from the floor is 5 feet 10 inches. The effective breadth of the room in the direction of the meridian is 19 feet 6 inches, and in the other direction (east and west) it is 14 feet. The distance between the north or south wall and the back of the corresponding collimator-pier is 13 inches. Hence, when the telescope is horizontal, the distance between its object-glass and that of either collimator is barely 3 feet. On account of the small dimensions of the room, I at first intended to place the collimators under proper protection outside it, but it was found |