ion kilometers, ers.) t last ion in space.

    As for Mason and Dixon, turned to England as scientific nersurn up atseminal events in eigury science, remarkably little is kno eit and feten references. Of Dixon tionary of National Biograpes intriguingly t o  t to tion to supply a plausible explanatory circumstance, and adds t Dur from ion hing more isknown.

    Mason is only slig in 1772, at Maskelyne’s be, ed to find a suitable mountain for tational deflectionexperiment, at lengting back t tain tral Scottis above Locay, and . urned to tkno eriously, urned up in P cly on titution.  been backto America since completing een years earlier and rons to greet er he was dead.

    ito survey tain, to Maskelyne. So for four montent in a remote Scottis ing a team of surveyors, ion. to find tain from all t deal oftedious calculating, for on ion at some pointon or around tain. It ially just a confusing mass of numbers, but tonnoticed t if o connect points of equal , it all became mucantly get a sense of tain.

    ed contour lines.

    Extrapolating from s, ton calculated t 5,000 million million tons, from  s and tcontour lines into t bad for a summer’s work.

    Not everyone isfied s, coming of t  it  possible to get a truly accurate figure  knoual density of tain. For convenience, ton  tain y as ordinary stone, about 2.5 times t of er, but ttle more ted guess.

    One improbable-seeming person ter ry parsonnamed Joe e and comparatively uation, Mic scientific teentury