3 ms·

http://books.google.co.uk/books?id=VAa-AouAHxoC&lpg=PA619&ots=uuQ_jFokE5&pg=PA619#v=onepage&q&f=false http://books.google.co.uk/books?id=VAa-AouAHxoC&lpg=PA61..

http://books.google.co.uk/books?id=VAa-AouAHxoC&lpg=PA619&ots=uuQ_jFokE5&pg=PA619#v=onepage&q&f=false http://books.google.co.uk/books?id=VAa-AouAHxoC&lpg=PA61...