242 Remarks on the Theory of Angular Geometry. [No. 123. 



good map, shewing not merely one high road through the country, but 

 also the principal cross-roads connecting the different parts of the coun- 

 try with each other. In point of fact, no one is considered to be master 

 of the subject, till he be pretty fully acquainted with these cross-con- 

 nections. 



We may chop logic as long as we please, but after all there is pre- 

 cisely the same difficulty in conceiving straight lines to be lengthened 

 by producing them, as in conceiving angles to be increased by the con- 

 tinued revolution of one of the sides about a point, or by the lengthening 

 of the circular arc measuring them. Each is accomplished by motion. 

 The straight line is produced by another straight line laid partly upon it, 

 and partly beyond it, or by conceiving the line to move along itself, all 

 points between the fore-end of the old line, and the rear end of the new 

 being common to both lines. In like manner, an angle or circular arc is 

 increased either by a line revolving about a point, or by conceiving the 

 arc to move upon itself, so as to have all the points between the fore- end 

 of the old arc, and the rear end of the new arc, common to both arcs. In 

 this way the idea of a fixed centre is unnecessary for any but the first 

 part of the arc, just as the idea of a fixed direction is unnecessary for 

 any but the first part of the straight line. 



Notes on the Recent Earthquakes on the North-Western Frontier. By 

 Lieutenant R. Baird Smith, Bengal Engineers. 



On the forenoon of Saturday, the 19th of February 1842, a severe 

 shock of an Earthquake was experienced at different points in the 

 countries on our North- Western Frontier, and extending thence it 

 affected, although with much reduced intensity, several of the districts 

 of the North- Western Provinces. 



The remotest point at which its devastating influence was experi- 

 enced, and relative to which any authentic intelligence has yet reached 

 us, was the city of Jellalabad, where extensive injury was done to the 

 fortifications and to the buildings throughout the place. The motion 

 of the earth is described as having been of an undulating character, 

 producing symptoms similar to those of sea- sickness in many of the 

 persons who felt it ; and in one account it is asserted, that the ground 

 opened and closed again with loud noise in several places. Such a 



