With regard to the question of injury to the eyesight from railway travelling, Dr. Lewis may again be supposed to speak authoritatively when he considers "it very injurious to allow the eyes to rest on external objects near at hand, such as telegraph-poles or wires, near trees or hedges, &c. whilst the train is in motion;" but, speaking of the same subject, he "does not find that in the travelling post-office much mischief is occasioned to the sight."[159] When we remember that the Post-Office work is generally performed by means of a strong artificial light, and much tedious deciphering of the addresses of letters necessarily occurs, as we have seen, during travelling, it must be admitted that the eyesight is here put to the strongest possible test. We have now traced our letter, posted in the metropolis, through the travelling post-office into the establishment of a provincial town. We shall follow it presently, and not leave it till it is properly delivered at the rural village to which we saw it addressed; but we must take the opportunities as they occur to describe with minuteness each particular, whether bearing directly or collaterally on our subject, as well as to add now and then a timely exhortation to the reader. Thus, you are indignant, perhaps, that a certain letter you ought to have had is not to hand at the proper moment, but has suffered some delay in transit. However, just think how many letters you do get, which come to your desk as true as the needle to the pole. Just listen to the old gentleman yonder as he tells how long the same business letter from a certain old-established house used to be in arriving, and what was paid for it when it did arrive. Above all, pray think of the travelling caged officials--those wingless birds of the Post-Office--and of what they go through o' nights in order that you may have your letter or your newspaper--posted yesterday in some quiet corner of the country 500 or 600 miles away--with your buttered toast to breakfast in town! A PROVINCIAL POST-OFFICE.