Thanks very much, but no tar

Dear Spurtle

On a point of historical road construction interest, could I respectfully point out that Hugh Lockhart (Letters, 3.5.13) uses the term 'macadamised' unduly loosely (in the context of the rest of his letter).  

Strictly speaking, macadamised road surfaces (introduced c.1820 by John Loudon MacAdam) consisted solely of compacted broken stone and gravel of carefully graded sizes – no tar was involved.  In other words, a surface not drastically dissimilar to the current surface of the Rocheid Path.

It was only later that tar/bitumen began to be used as a binding agent to make the surface dust free and capable of bearing greater loads – in other words, more suitable for the newly arriving motor car – a surfacing material which then evolved into tarmac as we know (and sometimes object to) it today.

Tim Smith
(Rosslyn Terrace)