602 
MARY GERTRUDE HASEMAN ON AMPHTCHEIRAL KNOTS. 
tion Di of the amphicheiral of the second order with fourteen crossings, No. 25 in 
the Plate. Its intrinsic symbol 
11 10 3 3 11 10 4 3 1 10 10 12 4 3 10 9 1 3 3 12 10 9 3 2 10 10 3 2 
shows that it is an amphicheiral of the first class of order 1 with one pair of 
amphicheiral centres. This is an example of Tait’s supposed third class (Trans. 
Roy. Soc. Edin., vol. xxxii, p. 499), which has the property of being changed into 
its own perversion by a single distortion, but, contrary to his idea, it must belong 
to the first class of order 1 and to the second class of order 2. 
It is of interest to note that all of those amphicheirals which belong simul- 
taneously to the first class of orders 1 and 2 exhibit two pairs of amphicheiral 
centres with the exception of one, which has fourteen pairs. 
