The operations for determining the longitude of Montreal were successfully concluded in September. In the spring (April and May) two series of observations were completed, the observers at Greenwich and Waterville (Ireland), and at Montreal and Canso (Nova Scotia), being interchanged between the two series, but no exchange of observers being made across the Atlantic. For the autumn operations Professor McLeod, of Montreal, came to England, and Mr. Turner crossed to Canada, and interchanges of observers were made as in the spring, between the pairs of stations separated by the cable.

The following table shows the number of nights of observation at the several stations in the four parts.

Signals were exchanged on each night between Greenwich and Waterville, between Waterville and Canso (the cable termini), and between Canso and Montreal. A few experimental signals were exchanged between Greenwich and Montreal, being automatically registered and repeated at the intermediate stations, but the results were not so satisfactory as those of the signalling independently in sections. Discussion shows that the transatlantic signals are practically as good as those over short land lines, excepting that the time of transmission is greater, and hence there is a larger chance of error from the necessary assumption of equality in the time of transmission in opposite directions.

The reductions are so far advanced as to show that the determinations in the spring and autumn for Waterville are accordant inter se, and agree with the geodetic determination within 2', i.e. well within the limits of error due to local attraction. The results for the transatlantic stations are also so far satisfactory, judged by the standard of accordance inter se.

The longitude of Paris was also redetermined in June and July (in the interval between the two series for Montreal), in concert with the officers of the French Service Géographique. Observations were made at Greenwich on seventeen, and at Paris on twenty nights. The reductions are not yet sufficiently advanced to pronounce definitely on the subject of the discordance found in 1888.

While in England, Commandant Defforges took the opportunity of swinging his pendulums at this observatory, and at Leith Fort, Edinburgh, where Captain Kater had made observations. Thus the French pendulum observations will be connected with the English and Indian.

The building of the south wing of the Physical Observatory was commenced in November last, and this addition will, to some extent, relieve the observatory of the present great pressure on available space; but the relief will not be by any means complete until the whole of the proposed cruciform building is finished.

The electric-light installation has been sanctioned by the Admiralty, and the details of the scheme are practically settled.

The volume of Greenwich observations for 1890 was passed for press in August last, and is being distributed. The volume for 1891, as was remarked earlier in this report, is not so well advanced as usual, but it is hoped soon to make good this deficiency.

In February, Captain Grant, R.E., of the Ordnance Survey, consulted the Astronomer Royal as to the determination of the boundary of Mashonaland, in concert with Portuguese officers. The most difficult part of this operation was the fixing of a meridian of longitude on the spot, and without, of course, any possibility of telegraphic communication. The method of

Moon culminations, observed with a small transit, was recommended; and a rough prediction of the Moon's errors was made for Captain Grant's use. A comparison of the prediction with observations since made is given in the Monthly Notices, vol. liii. p. II.

Captain Viniegra, director of the San Fernando Observatory, paid a visit to Greenwich on April 4, and discussed the work of the Astro-photographic Chart.

Sir G. B. Airy, late Astronomer Royal, who died early in the past year, gave another proof of his attachment to the Royal Observatory by bequeathing to it such of his books, manuscripts, &c., as might be considered useful; and Mr. Wilfrid Airy has accordingly transferred to our library 94 volumes, 134 unbound tracts, and the voluminous manuscript calculations of the Numerical Lunar Theory.

Royal Observatory, Edinburgh.

The contract for the buildings of the new Royal Observatory was signed on 1892 May 25, the work being entrusted to Messrs. W. and J. Kirkwood, of this city. The plans were prepared by Mr. W. Wybrow Robertson, of H.M. Office of Works. A short description of them will be useful in following the progress of the work already done.

The main building extends 180 feet from east to west, terminating in two towers surmounted by domes, or rather "drums." The eastern tower, rising to a height of 75 feet, will contain the 15-inch Grubb refractor, while the 24-inch reflector from Calton Hill will be mounted in the western dome, the top of which will be some 44 feet above the ground at that end. A single range of rooms, opening on a corridor on the south, extends from tower

to tower, only the end rooms occupying the whole depth of the building. The roof is designed as an asphalted platform, 113 feet long and 22 feet broad, affording free communication between the towers. Beginning from the west, the apartments are thus arranged: Spectroscope room, general laboratory (with three isolated piers), electrical room, cleaning room, mechanics' workshop, chronograph and class room. Light and dark photographic rooms, as well as a computing room for the equatorial and photographic work, are situated in the eastern dome. Several useful basement rooms adjoining the large tower have been constructed.

A central extension of the main building towards the south, measuring some 80 feet by nearly 24 feet, will contain the chief computing room, the hall, stairs, and ante-room, the director's room, and, lastly, the fireproof library-a lofty apartment 34 feet 6 inches by 23 feet 9 inches, with a light iron gallery affording access to the upper shelves. There is a top storey to the southern part of this portion of the building 66 feet in length, designed for optical work, into which a large beam of light can be reflected from a siderostat on the flat roof to the north. An iron railway down the centre of the room, insulated from the rest of the floor, will support the instruments. It will be seen that this room practically forms a horizontal telescope.

In the basement will be placed the heating apparatus, a dynamo and accumulators for supplying electricity for lighting the observatory and illuminating the instruments. In the observatory there will thus be only one chimney, the draught of which can be controlled when requisite.

The transit circle will be housed in a separate building eighty feet to the west of the western tower, accessible by a covered way. By means of light walls and roof of corrugated iron, shaded by louvres of tinned steel, it is hoped that uniformity of inside and outside temperature may be secured. As an extra precaution against the egress of warmer air immediately over the instrument, the opening in the roof will be at a lower level than the air-outlets in the eastern and western sections of the roof.

The remaining buildings are the astronomer's house, two assistants' houses, arranged as a double villa, and a gate-lodge.

Owing to the steepness of the approach, and partly also to the position of the site in a public park which rendered it undesirable to cut up the roadway, an inclined railway was made from a temporary siding at Blackford Hill Station on the Suburban Railway. At the siding are also the sheds at which the greater part of the stone cutting is done. Hence little dead weight beyond the prepared materials has to be hauled up the hill. The siding and inclined track were finished by the middle of August. Meanwhile the rock excavations for the library and other parts of the buildings had been in progress since July 1I, so that the first stone could be laid on the concrete bedding on

October 4. By the end of the year the whole of the main building with its east and west towers was well in progress. The walls are built of grey sandstone, from Hailes Quarry, to the west of Edinburgh, but are faced with a reddish freestone procured from Doddington Hill, in Northumberland.

Including the cost of drainage, water-pipes, pumpingchamber, and fencing, the expenditure at the close of the year was a little over 4,000l. Greater progress would have been made but for the severe frosts, which not only stopped all building, but also cut off the supplies of stone from the quarries.

At Calton Hill, Mr. Heath has carried on the time service, the meteorological reductions, and the preparation of weatherreturns for the Registrar-General for Scotland, as in previous years. The revision of the Edinburgh star places has also been carried a stage further. A redetermination of the latitude with the mural circle is also in progress.

In July, Lieutenant Gratzl, of the Austrian Navy, observed the times of vibration of a pair of invariable pendulums at Calton Hill, preparatory to a visit to Jan Mayen, where the observations were to be repeated.

Fifteen astronomical circulars have been issued in the course of the year. The thanks of observers are due to Messrs. Berberich, Schorr, H. Oppenheim, and Archenhold, for their important contributions to these circulars. No. 22 is specially interesting, as containing the earliest notice of the outbreak of Nova Auriga. It is almost superfluous to add that this wonderful object was first seen by Dr. T. D. Anderson, of this city, who also independently picked up Comet Holmes two nights after its discovery in London. The Nova was observed on every favourable occasion until its disappearance, not only at Calton Hill, but also at Dunecht, by Dr. L. Becker, who went there the moment the star's extraordinary character was perceived. The results of these observations are published in the Transactions of the Royal Society of Edinburgh (vol. xxxvii., p. 51). On its reappearance in the autumn, the star was again studied with the Dunecht refractor by Professor Copeland, with the valuable aid of Mr. J. G. Lohse, who was staying there for a short time. A later attempt made by Dr. Becker to secure a photograph of the spectrum was unsuccessful, owing, probably, to a want of sufficient clear sky for a lengthy exposure, for the same apparatus yielded a spectrum of Jupiter, full of minute detail.

In November and December Dr. Becker completely dismounted and packed the transit circle, together with the piers and collimators. The granite-work of these piers and their foundations is very beautiful and solid, and will be used again at Blackford Hill. The task of separating these massive cut stones was much lightened by the aid of the experienced and skilled mason, Mr. John Smith, who had erected them twenty years ago, and who, it is hoped, will rebuild them in their new quarters.

In continuation of his published work on the Low Sun Spectrum, Dr. Becker has reduced the late M. Thollon's Solar Spectrum to Rowland's wave-lengths and compared them with his own results. He has also revised the papers on Nebula and on The Latitude of Dunecht, mentioned in last year's report.

Shortly after the new year, Dr. Becker was appointed successor to the late Dr. Grant in the Chair of Astronomy in Glasgow.

Just before daybreak on the morning of March 8, fire broke out in the official residence of the Astronomer Royal for Scotland. When it was first perceived, one corner of the house was already burning fiercely, from foundation to roof-five stories in all. Happily the inmates escaped unharmed. Notwithstanding the promptest exertions on the part of the police and the fire-brigade, the corner where the fire broke out, the whole of the roof, and the top flat were destroyed by fire, while much injury was inevitably done to the rest of the house by water. Fortunately the library was not materially damaged, though for months the books required continual turning over to prevent the inroads of mildew. The most valuable works entirely escaped injury, owing to their position in well-glazed cases in another part of the house. Practically ten months were required before the house and library were again in order.

By an oversight, wrong figures were given for the latitude of the new observatory on p. 190 of Monthly Notices, vol. 1. The approximate latitude is 55° 55′ 28′′0.

Royal Observatory, Cape of Good Hope.

The inadequacy of the computing force for the past ten years has led to large and growing arrears of reduction which no effort on the part of the existing staff could overtake. The Lords Commissioners of the Admiralty having granted an addition to the computing staff, it appeared to H.M. Astronomer that the time had arrived to make a supreme effort to overtake these arrears. Accordingly, all meridian-observing not absolutely required has been suspended during the year; the assistants have thus been enabled to give much additional time to the work of reduction, and, as will be afterwards evident, a great amount of the arrears has been overtaken, although not so much as would have been but for the serious illness of two of the assistants.

The series of meridian observations of the Sun, Mercury, and Venus, with the brighter clock-stars, was continued until September 21, when it was interrupted by necessary repairs to the floor of the Transit Room and Central Hall. On removing the old flooring-boards of the Transit Room, it was found that the framework of beams supporting the floor, and even the strong wooden pillars which supported the roof, rested on the foundation of the transit circle piers. This explained the great difficulty which