NATURAL PHILOSOPHY. 151 



separate them from the larger quantities in which they are involved. The 

 results set forth by Col. Sabine to the British Association are as follows: 



1. The diurnal variation following in all places the order of solar time, and 

 being at its maximum about two hours after noon, changes its sign at the time 

 of the two equinoxes. Thus, while the maximum diurnal deflection from the 

 magnetic meridian is eastward in all places up to the 21st of March, a change 

 in the amount of deviation begins on the 22d, and is completed hi about ten 

 days, after which the maximum daily variation is to the westward, and at a 

 mean equal to the eastern variation of the preceding six months. 



2. There is an annual variation in the intensity of terrestrial magnetism, 

 of small amount indeed, but affecting both the northern and southern hemi- 

 sphere in the same manner, the intensity being greatest when the sun is in 

 perigee and least when it is in apogee. 



3. It is well known that all the instruments used in magnetic observation 

 are from time to time affected by disturbances, or storms as they are often 

 called ; these storms have been found to be subject to a periodic fluctuation, 

 and this period has been discovered to correspond with that assigned by 

 Schabe to the spots on the solar disc. 



4. It has been clearly shown that there is a variation in magnetic declina- 

 tion, dependent on the change of the moon's position in relation to the 

 meridian of the place of observation, and having therefore for its period, the 

 lunar day. This, although first inferred by Sabine from a single set of observa- 

 tions, has been since fully proved by Kriel. Finally, the hypothesis which 

 ascribes the variations in the phenomena of terrestrial magnetism to local 

 variations of temperature is completely refuted. 



May we not hope that the relations of the magnetism of the earth with the 

 heavenly bodies, which exert the greatest influence in other respects upon 

 our planet, having been thus conclusively shown, a basis is now provided 

 upon which to erect a science, that will be as simple in its laws and as 

 fertile in its results as the theory of universal gravitation ? Up to the present 

 time terrestrial magnetism as a science has had no other foundation than 

 vague or unsupported hypotheses, or empiric propositions, which, although 

 true, have been founded on no general law. Henceforth it would appear to 

 be as closely within the reach of mathematical methods as the tides. Proc. 

 British Association. 



ON THE CONSTRUCTION AND OPERATION OF THE SUBMARINE 



ATLANTIC TELEGRAPH. 



A recent writer in the London Times, reviewing the proposed construction 

 of the Submarine Atlantic Telegraph, sketches out the details and prospects 

 of the enterprise as follows: 



" The cable, to allow for the inequalities of the ground and other exigencies 

 of the case, will be 3,000 miles long. The wires will be isolated in gutta- 

 percha coatings ; and all the improvements which science can afford will be 

 applied to give durability, strength, and efficacy' to the cable. To lay so 

 enormous an amount of coil, two ships will proceed to the mid-ocean, each 



