COMPARATIVE METROLOGY. 379 



two-thirds of our acre. The former cause reduces it by about 

 five-sixths per cent., and the latter by about six, and we thus 

 get an approximate rule for converting jugera into acres, namely, 

 to take two-thirds of their number and strike off 7 per cent, 

 from the result. How the tradition of the jugerum ever got to 

 Ireland seems very hard to say. Perhaps it was not extinct 

 in England in the time of Earl Strongbow, at least I am much 

 disposed to recognize in the Irish acre, not three actus as in 

 the English, but five, which would of course make it 8000 yards. 

 But in order that its 160th part should be a square, it under- 

 went rather a greater modification than the English, losing about 

 2 per cent, and becoming a square of 7840 yards, the linear 

 perch being thus not 5j yards but 7. Here again my specu- 

 lation suggests an approximate rule to reduce Irish acres to 

 English ; multiply them by ten, divide by six, and diminish 

 the result by 3 per cent. Between these two acres stands in 

 point of magnitude the Scotch, but here we seem to come upon 

 a tradition of the direct kind, and I mean therefore to connect 

 it with that of the pezza from the jugerum. 



7. At page 163 of the 3rd volume of Miss Winkworth's 

 translation of Niebuhr's letters is one to Savigny, which offers 

 several points of interest as to the connection of ancient and 

 modern measures. He tells Savigny that at Eome there is no 

 manual of weights and measures, nor any information to be got 

 either from scholars or men of business, but that it having 

 occurred to him that during the French rule tables must have 

 been formed connecting their measures with the Roman, he had 

 been enabled to ascertain by accurate calculation the magnitude 

 of the pezza, and thus to show its near approach to the ancient 

 jugerum. Consequently the rubbio being 7 pezze represents the 

 old land allotment. The remarks on the depourvu state of Rome 

 as to information are in the querulous tone into which unhappily 

 Niebuhr often falls. The tables he speaks of having found are 

 doubtless those published but a very few years before, and of 

 which Prony has given an account at the end of his work on 

 the drainage of the Pontine Marshes. If this commission had 

 ceased to exist in 1818, when Niebuhr wrote, its previous exist- 

 ence must at any rate have been matter of notoriety, and it is 

 hard to believe either that all the commissioners had left Rome 



