THE MAGNETIC SURVEY OF NEW ZEALAND. {Specially written for Progress).

Progress, Volume II, Issue 8, 1 June 1907, Page 285

THE MAGNETIC SURVEY OF NEW ZEALAND. {Specially written for Progress).

Anyone making a tour of the scattered groups of islands lying to the south of New Zealand, will learn of the numbers of vessels that have gone to pieces on their rugged shores. They will, however, find that the government is fully aware of the dangers to which mariners are exposed in regard to these islands ; a fact evidenced by the various depots established. All the principal islands are provided with supplies of food ior use of unfortunate castaways, and finger posts erected in conspicuous places indicate the direction in which the nearest depot lies. Not only this much, but boats are stationed at certain points so that depots otherwise inaccessible may be reached. If then these dangers exist, and have proved so disastrous in the past, it is but reasonable to argue that with the increasing prosperity cf New Zealand, the shipping industiy will also increase. More ships and larger ships with augmented speed will be demanded and these, be it noted, will all be of iron. Everyone knows the necessity of the compass in navigation, but few are aware of the complicated corrections required on an iron ship. Bars of iron, and large balls like heavy shot are disposed around the compass,- all requiring to be placed with the greatest accuracy. Given perfection in this respect, corrections have to be applied according to locality, and these are calculated by means of charts. The charts, therefore, must also be accurately prepared and the larger the number of observations made at different stations the lower the percentage of error. The recently completed magnetic survey of New Zealand shows that an error of threequarters of a degree exists in the present charts; and this, though perhaps not very serious, is, from a scientific point of view, distinctly inaccurate. The Magnetic Survey of New Zealand was first mooted in 1897, and became an established work by a resolution passed at the Sydney meeting of the Australian Association for the Advancement of Science in 1898. This resolution was supported in New Zealand, by the Shipping Master at Wellington, and the Chamber of Commerce in Christchurch. The Royal Society of I^ondon gave evidence of practical support by the offer of the necessary instruments, and this offer being gratefully accepted, operations were begun in 1899 under the control of Dr. Coleridge Farr, of Canterbury College, Christchurch, and were continued as opportunity occurred until their completion last year. This undertaking will prove of great scientific import, and the value of the work achieved resulted in the equipment of the " Discovery," which recently visited the Antartic as a magnetic survey ship. The work also induced Mr. G. Heimbrod to visit New Zealand in magnetic survey interests ; and it is likely that the American ship " Galilee " engaged in the magnetic survey of the Pacific, will voyage to New Zealand this year for the comparison of instruments. A few years ago, the International Magnetic Conference decided that it was most desirable that a complete magnetic survey of the Globe should be undertaken and completed, if possible, within fifteen years As before mentioned, the survey of New Zealand was concluded last year and the reductions are now in progress. The American authorities, under the presidency of Dr. I v . A. Bower,

though fully recognising the value of the admirable work already accomplished, have made a request that the work should be extended to the outlying islands of New Zealand also, and, further, that Macquarie Island should be included. This island though politically under the jurisdiction of the Commonwealth is physically of interest to New Zealand, and it is highly desirable therefore, that its magnetic position should be accurately determined.