4 REPORT — 1842. 



under a revised system of instructions, it will be found necessary to introduce, 

 will now be based on mature experience, and adopted with sound deliberation. 

 Uniformity can now be insisted on in points which were necessarily at first 

 open to peculiarities of local and individual practice. Hourly in place of two- 

 hourly observations may possibly be found generally practicable. Instrumen- 

 tal corrections, and especially that for the temperature of the magnets, which 

 has proved to be the most important of all, as well as the most difficult to as- 

 certain, will have been accurately determined, and can henceforward be con- 

 fidently applied. 



But in regarding what has been done as preparatory to what is to follow, 

 we are not to lose sight of its actual independent value. Were it only on ac- 

 count of its affording so vast a basis of comparison with the itinerant results 

 of the antarctic expedition, it would have been inestimable. The demonstra- 

 tion it has afforded of the ubiquity over the whole globe of those singular dis- 

 turbances to which the name of Magnetic Storms has been applied, could 

 have been no otherwise obtained, and is in itself a physical result of the first 

 importance. The data it has afforded for the revision of the Gaussian theory 

 are numerous, and beyond all comparison more exact than any which had ever 

 before been collected. In a word, were the series broken off at this point, 

 though we must have grieved to find ourselves arrested in full career, we 

 should stillhave found cause to regard the operation as conspicuously successful. 



3. Magnetic Surveys. 



Southern Africa. — Lieut. Clerk, R.A., who is noticed in the last Report as 

 having been ordered by the Master-General of the Ordnance to join the mag- 

 netic observatory at the Cape of Good Hope, in anticipation of an application 

 for this survey, arrived at the Cape in December, and has since taken part in 

 the duties of the observatory as assistant to Capt. Wilmot. In the estimate 

 which has been forwarded to the Treasury of the expenses of the magnetic 

 establishments under the department of the Ordnance for the newly autho- 

 rized period, Lieut. Clerk and one additional gunner are included in the 

 strength of the Cape observatory, the survey having been made part of the 

 duties of that establishment. It is proposed that the survey shall comprehend, 

 in addition to the colony itself, as extensive a portion of the earth's surface in 

 all directions from the observatory as time and circumstances will permit. 

 Application has been made to the Admiralty (who have on all occasions shown 

 the utmost readiness to promote magnetical inquiries.) to permit the sea por- 

 tions of this survey to be carried into execution by occasional opportunities 

 which the Admiral at the Cape station may be able to afford without prejudice 

 to the public service in other respects, in Her Majesty's ships and vessels 

 under his command. This will include the coasts of Africa on either side of 

 the Cape. When this portion of the survey shall have been considerably ad- 

 vanced, we shall be better able to judge of the expediency of completing the 

 circle by an excursion into the interior. With a view to this, inquiries have 

 been set on foot at the Cape, and answers received from the colonial autho- 

 rities in the commissariat and surveying departments, relative to the most de- 

 sirable route, the strength of the party, time required, mode, and probable 

 cost of transport and subsistence, &c. The Geographical Society have also 

 furnished notices of high interest as to the points of geographical discovery 

 (including the discovery of the Great Lake in the interior of South Africa, 

 whose existence is considered certain, but which has never been visited by 

 any European), which might be accomplished consistently with the objects of 

 such survey. 



North America. — Lieut. Lefroy, R.A.,has been appointed successor to Lieut. 



