OTAGO INSTITUTE.

Evening Star, Issue 3169, 17 April 1873, Page 2

OTAGO INSTITUTE.

There was a meeting of the Institute last evening, at which Mr R. Gillies presided, and about a dozen members attended. There was some preliminary business, consisting of the acknowledgment of the receipt of charts from the Chief Signal Officer of the United States, the election of the Rev. E. G. Penney as a member, and the alteration of the financial year, so as to commence in January and end in December, after which three papers were read. Mr A. E. Ross read a paper “On the variation of the declination of the magnetic needle in the southern portion of the Middle Island, and remarks on the desirability of establishing magnetic observatories in New Zealand.” Ee explained that when a magnetised steel bar, on a vertical axis through its centre of gravity, on which it was free to revolve, the axis being between its poles, it would oscillate on each side of a certain determinate position, in which, at length, it would come to rest. When in that position, a vertical plane passing through the axis and the poles was called the magnetic medium. This plane generally made an angle with the true meridian of the plane in which the magnet was situate. This angle was called the declination of the magnet. It was, perhaps, better known to British sailors and others as the variation of the compass, and it was to that property of the magnetic needle that he proposed to direct attention in his short paper ; more particularly, however, to some remarkable variations in declination which occurred in different localities in this Province, which had come under his notice. The declination of the magnetic needle was subject to variations of several kinds ; secular variation, annual and diurnal variation, and accidental variations or perturbations. In addition to these secular, annual, and accidental variations, each of which he explained, there were local variations, many of which in this Province had been of a most remarkable character. The variation in the declination of the needle, as determined from astronomical observations taken on board ship in the vicinity of this coast line, was stated in the Admiralty charts to be progressing in an eastcily direction at the rate of nearly 2min. per annum. He then sketched the observation of Captain Stokes, of H.M.S. Acheron, in 1851; those of the late Mr Kettle in 1852 ; Mr J. T. Thomson’s in 1857 ; and Mr MTverrow’s in 1861. Mr England, who triangulated the Moeraki and Hawksbnry districts, informed him that in many other localities the aberration of the magnetic needle prevailed to such an extent at the time he was engaged on his survey, that it was in some cases a matter of great difficulty, and in other? quite impossible for him to delineate accurately the topogiaphical features of country from compass observation—and that the disturbing elements of that district exerted their influence beyond the limits of the district was evidenced by the fact that captains of coasting steamers complained of irregularities in their compasses when sailing along the Moeraki coast. Ee did not intend to put forward any theory accounting for those differences. His object was simply to direct attention to a department of science the existence of which seemed in New Zealand to have been wholly

forgotten, and to suggest the desirabilitynay, the necessity—of establishing magnetic observatories in the Colony, where regular md systematic observations might be made of those ever-varying, ever-interesting phenomena. He thought that no person would deny the desirability, and that the necessity existed would be apparent, when he told them that for scientific purposes the result of the observations he had noted were of comparatively little value ; and to say that was not disparaging to the observers, who, he had no hesitation in saying, had taken those observations carefully and accurately ; but when they considered that the results obtained by the celebrated Halley, on a voyage made expressly to collect the data necessary to determine the elements of magnetic geography, “were deprived of the chief part of the advantages which ought to have attended them, because of the absence of uniformity in Lis instruments, and the neglect of making proper comparisons of them with others,” they need not wonder that results obtained by surveyors when prosecuting their routine duties, were from similar causes of little value; and of least value when at the place of observation magnetic disturbance prevailed to the greatest extent. In conclusion, he suggested r 1. That a set of magnetical instruments similar to those supplied totheColonial observatories at Canada, St. Helena, Cape Colony, Van Diemen’s Land, Victoria, and India, be furnished to the observatory at Wellington, and placed under the supervision of Dr Hector, Director of the Geological Survey, or some other competent officer. 2. That a declination compass and dipping needle be supplied to the meteorological observatories in each Province, Some Provinces might possibly be already possessed of some of the required instruments. A very excellent declination compass was, he knew, among the stored instruments belonging to the Provincial Government, and which, he thought he was correct in stating, had not during a dozen years been taken out of its box except once, when it bad been taken out in order to be shown along with other scientific instruments at the exhibition held in Dunedin eiuht or nine years ago. 3. That syste. matic and regular observations be taken at each station; and, lastly, that at out-stations where any remarkable features presented themselves—as at the Bluff, Observation Point, Mocraki and Kauroo districts in this Pro-vince-periodic observations be made under assimilated conditions. If those suggestions were acted on, then he believed that New Zealand would be in a fair way to take a prominent part in removing the veil, which yet concealed from mankind what might be termed the moving mysteries of terrestial magnetism. A paper by Mr Petek Thomson, entitlad “A Visit to Sandymount, with a brief description of some of its most natural features,” was also read, and Mr A. C. Purdie described a specimen of the yrampua pkocam orca of Owen, which was killed at the Heads by the Maoris, and obtained from them for the museum by the Hon, Capt. Fraser. It has a very formidable-looking head, and large laniariform teeth, well adapted for tearing and destroying whales. The Maoris call them killers, say that they attack whales and tear out their tongues. He had had a photograph taken of this specimen, and forwarded to Dr Hector, in the hope that scientific men might take up the subject and give some information regarding the animals frequenting our coasts, as there was great uncertainty regarding their history.