measuring the different degrees cf Magnetic Intensity. 379 



over the surface of the earth ; and, as it will, like every other 

 fluid of this sort, be in its greatest force when the sun's action 

 is greatest., it might, in opposition to the repeUing force of the 

 magnet, bring them nearer the exact direction of the magnetic 

 meridian or line in which the current moves. 



But whether this cause assigned be correct op not, I cannot 

 help concluding that all the general results drawn from the ob- 

 servations made hitherto on the magnetic intensity that prevails 

 in different parts of the globe, by the vibrations of the magnet, 

 must necessarily be erroneous, except they were all made in the 

 same season of the year, and at the same time of the day, which, 

 certainly, was not the case : For it is obvious that, on the same 

 spot, there is double the force of magnetic intensity in a clear 

 day in June, to what there is in a frosty day in November. On 

 the 11th of last November, the thermometer standing at 31% 

 the magnetometer stood at 14°. 



Lest the magnets had lost any portion of their strength, two 

 large magnets were passed over them in November ; but they 

 had lost no part of it 



Notice of an Experiment which proves that the Magnetic Needle 

 does not point North and South ; hut only when it is suspend- 

 ed in a position approaching to the horizontal, or so that it 

 cannot shew its natural bearings. By Mark Watt, Esq. 

 M. W. S. * Communicated by the Author. 



A o the extremity of a small slip of wood of any length (three 

 inches for example), let one of the ends of a thin bar of steel of 

 two and a-half inches long be affixed, so that both shall form one 

 straight bar, and let this be balanced in an horizontal po- 

 sition, by a small short cross bar, passing through the other 

 wooden bar at right angles, at the distance of half an inch from 

 the end to which the piece of steel is attached ; and let two small 

 pivots be formed at the ends of the cross bar, so that it may vi- 

 brate upon two rests hke a balance, or dipping needle. 



If we then render the thin bar of steel fixed into the wood 

 fully magnetic in the usual way, making the farther extremity 



• We recommend Mr Watt to consult the Memoirs and great work on 

 Magnetism by Hansteen.— JBdit. 



2 



