By 1855, at least, a modified form of the concentric ring cancellation was introduced. This had a number in the center in large figures, some 8 mm. high, with four concentric circles enclosing it, the outside diameter being about 23 mm. This type was generally struck in black, but is sometimes found in a dull blue also. It can be seen on the strip of stamps numbered 81 on Plate V. The numbers, of course, were placed in the cancellations with a definite purpose, and a little study of entire covers shows that certain numbers were assigned to certain post offices, as might be suspected. Number 21, for instance, is the most common one and will be found to be connected with Montreal. Further study will reveal the fact that the names of the post offices were taken in alphabetical order, and the numbers assigned to them consecutively in that way. Still further inspection develops the fact that most of the post offices were those in Upper Canada (or Canada West), while but a few of the most important ones were included from Lower Canada (or Canada East.) Mr. Edgar Nelton seems first to have made a study of these numbers in an attempt to identify their corresponding post offices, and he published a list of some twenty-two as the result of his examination of many original covers.[78] The numbers run up to 52 at least, and using the facts that we have deduced concerning the arrangement of the names, we have endeavored to fill out his skeleton list with such offices as it seems possible may yet be identified with the corresponding numbers. We have done this with some assurance for the following reasons:-- [78] =Chicago Collectors' Monthly, II=: 21. We were fortunately able to examine a Canada Directory for 1857-8, and on looking up the postal information given therein, found a list of the money order offices then existing. This was in two sections, the first containing the names, alphabetically arranged, of 31 offices in "Class No. 1," which included most of the principal cities and towns; and the second a lengthy alphabetical list of offices in "Class No. 2." The first section had a somewhat familiar appearance, and inspection showed that a majority of the names on Mr. Nelton's list of numbered cancellations were there in proper order! But 21 more names were needed, according to the cancellation numbers, to fill out the latter series. The second section was therefore examined for such towns as had the largest populations and were presumably most important. The result enabled more than one name, already on Mr. Nelton's list, to be fitted in its proper place! Here, then, was apparently the solution of the first series of numbered cancellations, and we hazard a guess that the 52 names are the original list of money order offices, arranged when the money order system was instituted in February, 1855.