ON MAGNETICAL AND METEOROLOGICAL OBSERVATIONS. 5 



Riddell, in the principal direction of the observatory at Toronto, and of the 

 survey there, which, as at the Cape of Good Hope, is made a part of the ge- 

 neral duties of the establishment. Having been relieved at St. Helena by 

 Lieut. Smyth, Lieut. Lefroy is now in England preparing instruments for the 

 survey, and will proceed to America in a few weeks. Since Lieut. Riddell's 

 return to England in January 1841, on account of health, the observatory at 

 Toronto has been conducted in the most satisfactory manner by Lieut. Young- 

 husband on the excellent system established there by Mr. Riddell. Exten- 

 sive as is the field of research which now opens in that quarter of the globe, 

 and arduous as will be the task of profiting duly by the opportunities likely 

 to be afforded, the zeal, intelligence, and perseverance which have been al- 

 ready shown by Messrs. Lefroy and Younghusband, give the best assurance 

 of the good performance of the further service entrusted to them. The Hud- 

 son's Bay Company, with its accustomed readiness to promote scientific in- 

 quiries of all kinds in their extensive territories, have most liberally under- 

 taken to furnish conveyance in the summers of 1843, 1844, and 1845, over 

 the countries to the north and west of Canada, extending to the shores of 

 Hudson's Bay and to the Pacific Ocean, and have made the further offer of 

 a passage in one of their annual ships from Hudson's Bay to England, so as 

 to include in the survey the interesting magnetic region of Hudson's Bay 

 and Straits. 



The operations thus contemplated in the north will connect themselves 

 with magnetic surveys actually in progress by several distinguished magneti- 

 cians in the United States. Mr. Bache has during the last summer com- 

 pleted the systematic survey of Pennsylvania, commenced in the preceding 

 year, including the three elements of Declination, Inclination, and Intensity. 

 Professor Loomis has extended his series of observations of the Inclination 

 over many parts (previously unvisited by him) of the States of Ohio, Indiana, 

 Illinois, and Missouri. M. Nicollet has also observed in the same region, and 

 Dr. Locke has added a contribution. These and other similar operations 

 which we may expect in the United States, from the increasing interest which 

 magnetism excites there, will connect the Northern British survey with the 

 determinations of Captain Barnett, R.N., commanding H. M. S. Thunder, on 

 the southern coasts of the United States and in the Gulf of Mexico. Cap- 

 tain Barnett is well provided with instruments both for sea and land observa- 

 tion, and has shown himself a zealous and careful observer. 



4. Observations made at Sea. 



It has already been stated in the last year's Report, that by the use of Mr. 

 Fox's instrument the inclination or dip, and the magnetic intensity may be mea- 

 sured at sea, if not with absolutely the same pi'ecision as at land, yet with a 

 precision quite as great as is requisite for every possible use to which obser- 

 vations at sea can be turned, that is to say, for the purpose of tracing out the 

 isodynamic and other magnetic curves in the portion of the globe occupied by 

 water ; and the probable absence of local attractions and disturbances in open 

 ocean, while it renders such curves more easily traceable, so it affords a ready 

 method of checking each particular observation by reference to the chain of 

 determinations of which it forms a part. To extend and facilitate the use of 

 this valuable instrument, a set of instructions for its use has been drawn up 

 by Col. Sabine, and printed by the Admiralty for general circulation. The 

 use of this instrument has been adopted by Captain Blackwood in his sur- 

 veying expedition to Torres Strait, and the same system of daily observation 

 is practised with it, as in the Erebus and Terror ; and the example it is to be 

 hoped will be followed, not only in voyages designed expressly for purposes 



