To this place, it is no longer a toilsome journey from Boston. Three-quarters of an hour, in a very commodious railway-carriage, brought me into the centre of the town, when a most interesting sight presented itself. The railway had been pouring in for the occasion upwards of 20,000 persons; and in the streets, all was bustle and harmony; thousands of well-dressed persons--some of the females elegantly so--moving in throngs here and there, all bearing the tokens of comfort and respectability. The occasion of the gathering is called the Mechanics' Fair, held for a fortnight, during some days of which all mill-work is suspended; the attraction consisting of a horticultural and cattle show, and an exhibition of the products of art and manufactures of the county, which is Middlesex. The horticultural show was in the Town-hall, a large, handsome apartment, with long aisles of tables, covered with piles of fruits and vegetables; and such fruits! peaches, nectarines, apricots, and the choicest plums, all of open-air growth, and not surpassed by any I have seen--fully equal to the best hot-house productions of England. Vegetables also very fine, all equal to the finest, except the turnip, which in New England is small. The flowers as beautiful as in the Old Country, but much smaller; consequently, that part of the show was much inferior to our shows of the kind. In the evening of each day, the fruits are put up to auction, and a good deal of merriment is caused by this part of the entertainment. Those who supply the show are well paid, as each morning there is a fresh supply; thus proving that it is not the selected few that are exhibited, but the average produce of the county.