The day of publication falling one day earlier in the calendar each year, has gradually antedated the issue of our jour nal, causing thereby a serious inconvenience to ourselves, and one that has been noticed by many of our renders. We prefer in this matter not to be so far in advance of the actual time, and in order to correct the discrepancy between the date of the paper and the day of actual issue, we seize the opportunity now offered at the beginning of the new volume, to defer the issue of the first number one week. By this arrangement none of our subscribers will lose anything, as we have already published two complete volumes, of twenty-six numbers each, for 1869, and before the 1st of January the first number for the year 187Q will be published and mailed to all our subscribers. With the present number we send out a supplement of the SCIENTIFIC AMERICAN to all our readers, which contains a large and fine engraving of the 11 ail way Bridge over the Susquehanna river at Havre de Grace, also a calendar for 1870. This supplement has been printed at considerable expense, and is sent free to all our subscribers. We would regard it as a special favor if they would post it up conspicuously where it may be seen, as it con-tai ,s our annual prospectus. Subscriptions are coming in very rapidly, and present indications encourage us to believe that our circulation will be very much increased on the new volume.