Table of Si?ies to Centesimal Parts of the Versed Sine. 99 



Let us now turn our attention to that part of thedistrict which 

 is situated on the south side of the Tyne. At Jarrow, two miles 

 west of South Shields, the well-known high main seam of coal 

 is nearly two hundred fathoms below the surface of the earth, 

 but in the vicinity of the latter place the accompanying section 

 gives us a depth of about seventy-nine fathoms. This re- 

 markable difference is not owing to any considerable inequa- 

 lity on the surface, but from the coal-measures here rising at 

 an unusual angle to the east. It was long ago observed by the 

 viewers or professional men here, that from the neighbour- 

 hood of Heworth the high main coal, the very best seam on 

 the Tyne, or even in the north of England, became injured 

 as it proceeded in a south-easterly direction, by being inter- 

 stratified by a band of coal of inferior quality with an admix- 

 ture of stony matter and iron pyrites. This they called the 

 Heworth Band; and though borings were made near the 

 Scots House in the vicinity of the Boldon Hills, there appears 

 not to have been sufficient encouragement resulting from the 

 trial to induce one of the most enterprising and opulent coal 

 owners of his day to prosecute the undertaking by sinking a 

 shaft. Owing to the high main coal being deteriorated by 

 this band, an opinion prevailed very generally, even among 

 professional men, that no mine would be worked to profit 

 near or under the magnesian limestone formation ; and as far 

 as the high main seam was the object of their speculations, 

 they were not far from the truth. I am not aware that the lime- 

 stone was ever thought to be the direct cause of rendering 

 the coal of inferior quality; but one thing was certain, that 

 whenever the collieries on the south side ofthe Tyne extended 

 their workings in the direction ofthe limestone hills, the He- 

 worth band was sure to intervene and injure the coal. How 

 far this is the case to the southward, will appear when the sec- 

 tion of Hetton Colliery comes under consideration. 



[To be continued.] 



XVIII. Table of the First, Second, and l^hird Powers of the 

 Sines to Centesimal Parts ofthe Versed Sine. By B. Bevan, 

 Esq. 

 To the Editors of the Philosophical Magazine and Journal of 



Science. 

 Gentlemen, 

 f T , HE following table of the first, second, and third powers 

 ■*• of the sines to centesimal parts of the versed sine, will be 

 found useful in several calculations. Perhaps they will be al- 

 lowed to occupy a place in your Magazine. 



Yours truly, B. Bevan. 



G2 



