216 BERTHA'S VISIT TO HER 



must also be destroyed, as the beauty of the lace 

 is greatly increased by the hard crisp look of the 

 main thread; and to effect this, the lace is 

 usually drawn over a line of gas flame, so as to 

 pass a current of heat through the open spaces. 

 It has been^bund, however, that even the com- 

 bustible net-work of lace stops the ascent of the 

 flame, in the same manner that the wire-gauze in 

 Sir Humphry Davy's beautiful lamp prevents it 

 from communicating with the inflammable gas in 

 a mine. In the new method, to overcome this dif- 

 ficulty, a horizontal tube is placed a little above 

 the lace, with a narrow slit j ust over the line or sheet 

 of flame ; and an air-pump being applied to the tube 

 and rapidly worked, a strong draft is produced into 

 the slit to replace the exhausted air. This draft 

 draws up the flame along with it, in spite of the in- 

 tervening meshes of the lace, and thus singes away 

 the useless fibres within^ as well as without. 



In the course of our journey from Llangollen 

 to this place, my uncle frequently made us ob- 

 serve the judgment with which the new road has 

 been laid out by Mr. Telford, the same engineer 

 who constructed the Llangollen aqueduct. In 

 such a mountainous country it was impossible to 

 avoid all hills ; but by gradually winding up their 

 sides, or by cutting the road out of the face of 

 almost perpendicular cliffs, he has preserved one 

 uniform and easy slope to the top of the highest 

 ground, over which it passes ; and yet at the same 



