TBANSA€TIONS OF SECTION A. 557 



8. An improved Form of Clinometer. By John Hopkinson, F.L.8., F.G.S. 



A ' day-and-night ' compass-card is set to true N. over the compass-needle 

 which necessarily points to magnetic N. The diameter of the card is less than the 

 length of the needle, the points of the needle therefore projecting beyond the card, 

 so that the correction made is seen and can be adjusted wlien required. The same 

 result woidd be attained by placing the card below the needle. The clinometer 

 ' dip ' is as usual below the magnetic needle, and can be easily seen outside the 

 compass-card. The advantage of being able to take the amount and direction of 

 the dip of strata with a single instrument without loss of time and liability to error 

 in making the correction for magnetic deviation, and at the same time having the 

 points of the compass exposed for more minute observation, must be obvious. 



