BRITISH SCIENTIFIC ASSOCIATION. 467 



tidered are all referable to the sun as their cause. Prof. Kreil discovered, however, 

 that another body of our system — namely, our own satellite — exerted an effect 

 upon the magnetic needle, and that the magnetic declination underwent a small 

 and very regular variation, whose amount was dependent on the lunar hour angle, 

 and whose period -was therefore a lunar day. This singular result was subsequently 

 confirmed by Mr. Broun in the discussion of the Makerstown Observations ; and 

 its laws have since been fully traced, for all the magnetic elements, by General 

 Sabine, in the discussion of the results obtained at the Colonial Magnetic Observa- 

 tories. 



**************** 



" The most important step which has been recently taken in this country to 

 advance the science of Meteorology has been the formation of a department 

 connected with the Board of Trade, for the collection and discussion of meteorological 

 observations made at sea. The practical results of a similar undertaking in the 

 United States are now well known. The charts and sailing directions published by 

 Lieut. Maury have enabled navigators to shorten their passages, in many cases by 

 one-fourth of the time, and in some even to a greater extent. The commercial 

 importance of such a result could not fail to attract general attention ; and accord- 

 ingly, when the United States Government invited other maritime nations to 

 co-operate in the undertaking, the invitation was cordially accepted. A conference 

 was held at Brussels in 1853, at which meteorologists deputed by those powers 

 attended ; and a Report was made, recommending the course to be pursued in a 

 general system of marine meteorological observations. This Report was laid 

 before the British Parliament soon after, and a sum of money was voted for the 

 necessary expenditure. The British Association undertook to supply verified 

 instruments by means of its Observatory at Kew; and the Royal Society, in con- 

 sultation with the most eminent meteorologists of Europe and America, addressed 

 an able Report to the Board of Trade, in which the objects to be attended to, so as 

 to render the system of observation most available for science, were clearly set 

 forth. With this co-operation on the part of the two leading scientific societies, the 

 establishment was soon organized. It was placed under the direction of a distin- 

 guished naval officer, Admiral FitzRoy ; and in the beginning of 1855 it was in opera- 

 tion. Agents were established at the principal ports for the supply of instruments, 

 books, and instructions ; and there are n,ow more than 200 British ships so furnished, 

 whose officers have undertaken to make and record the required observations, and 

 to transmit them from time to time to the Department. The observations are 

 tabulated, by collecting together, in separate books those of each month, corres- 

 ponding to geographical spaces bounded by meridians and parallels 10 degrees 

 apart. At the present time, 100 months of logs have been received from nearly 

 100 merchant ships, and are in process of tabulation. Holland is taking similar 

 6teps ; and the Meteorological Institute of that country, under the direction of Mr. 

 Buys Bellot, has already published three volumes of nautical information, obtained 

 from Dutch vessels in the Atlantic and Indian Oceans. For the purposes of meteor- 

 ological science, this system cannot be considered as complete until observations on 

 land are included. Most of the greater atmospheric changes are due to the distri- 

 bution of land and water, and to the different effects of the sun's rays on each 

 Observation alone can furnish the data from which the effects of these agencies 

 may be calculated ; and we can therefore probably make no great advance in the 

 knowledge of the meteorology of the globe, without a concurrent investigation of 



