Clarke,Alexander Ross(1873),"XIII. Results of the comparisons of the standards of length of England, Austria, Spain, United States, Cape of Good Hope, and of a second Russian standard, made at the Ordnance Survey Office, Southampton. With a preface and notes on the Greek and Egyptian measures of length by Sir Henry James",Philosophical Transactions(London)163: 463,doi:10.1098/rstl.1873.0014