When my pupils have gained the quick perception and instantaneous apprehension which always reward the studious use of In., Ex., and Con., they can, amongst other new achievements, always remember and never forget figures and dates. _Pike's Peak_, the most famous in the chain known as the Rocky Mountains in America, is fourteen thousand one hundred and forty-seven feet high. Instantly, one who is trained in the use of In., Ex., and Con., perceives that there are two fourteens [Syn., In.] in these figures, and that the last figure is half of fourteen, or 7 In. by W. and P., making 14,147. Of course, one who is not practised in analogies, in discovering similarities and finding differences would not have noticed any peculiarity in these figures which would enable him to remember them. Few people ever notice any relations among numbers. But any possible figures or dates always possess relations to the mind trained in In., Ex., and Con. _Fujiyama_, the noted volcano of Japan, is twelve thousand three hundred and sixty-five feet high. Does any pupil who has mastered the first lesson and who is expert in the use of In., Ex., and Con., fail to notice that here we have the disguised statement that the height of this mountain is expressed in the number of months and days of the year, 12,365 feet high? These figures drop into that mould and henceforth are remembered without difficulty. These are remarkable coincidences no doubt, but are not all sets of figures similarly impressive coincidences to the trained eye, and the _active_, _thinking_ and _assimilative_ mind? No reader of English history has failed to notice the three sixes in the date of the Great Fire in London, _viz._, 1666. The "three sixes" are generally resorted to as a signal for fire companies to turn out in full force; yet such a coincidence of figures in a distant date makes a slight impression compared to the vividness of events that happened in the year of our birth, the year of graduation from school, the year of marriage, and the year of the death of relatives, &c., &c. Keep a small blank book for such entries, not to help remember the dates or facts, but to have them together so as to rapidly deal with them, to classify them and otherwise study them under the eye. You will soon be astonished at the accumulation. The population of New Zealand, exclusive of natives, is 672,265. Bringing the first two figures into relation with the last two we have 67 and 65--a difference of 2 only. The two groups of 672 and 265 have the figure 2 at the end of the first group, and another 2 at the beginning of the second group. These two twos are in sequence (Con.), and each of them expresses the difference between 67 and 65. _Thought_ about in this way, or in any other, the series becomes fixed in mind, and will be hard to forget.