Description of a Portable Levelling Instrument. 99 



attentive, and obliging, in all the relations of life / and he was 

 most warmly loved by all who knew him best. 



It is probable that intense application to his labours laid the 

 foundation of the disease — consumption of the lungs — of which 

 he died. The symptoms of the fatal malady began to mani- 

 fest themselves in the autumn of 1836 ; but he was able to 

 continue at work, although with many interruptions, until 

 within two or three months of his death, which happened on 

 the 15th January 1838. 



Throughout the whole of his illness, he maintained the 

 same meek and quiet deportment which ever distinguished 

 him. He spoke little ; but that little proved how much his 

 spirit was cheered by Christian faith and hope, and discovered 

 on what a deep foundation were based the remarkable humi- 

 lity, simplicity, and sincerity, which formed the chief orna- 

 ments of his character, and endeared him to all connected 

 with him. 



March 30. 1844. 



Description of Portable Levelling Instruments, By David 

 Stevenson, F.R.S.E., F.R.S.S.A., Civil Engineer, Edin- 

 burgh. Communicated by the Royal Scottish Society 

 of Arts.* With a Plate. 



In examining a tract of country, I have often experienced 

 the want of some portable, and, at the same time, accurate 

 instrument, for ascertaining, in a general manner, the rela- 

 tive levels of different points, previous to determining the 

 line of a more detailed survey. A small spirit-level without 

 any telescope, having a common sight and cross-hair attached, 

 is sometimes used for that purpose, being fixed on a staff 

 stuck into the ground. The large instruments commonly 

 used in levelling are also often employed, but neither of these 

 instruments answers the object I had in view ; the first being 

 much too rude for the required accuracy, and the second too 



Read before the Society, 12th February 1844. 



