A letter from Lowell to the Boston 'Traveler says :—The " spindle city " is gradually resuming its steady hum of industry and wonted business-like appearance. With the exception of tho unfortunate Middlesex, most of the mills are in running condition, giving the operators from two-thirds to full time. The cold snap and light flurry of snow, which, by the way, is giving us excellent sleighing, has had the effect of making trade look up, for it has brought in a good sprinkle of our rural neighbors, who, with their produce, generally have a little ready cash on hand for investment in dry gc&ls, groceries, &c, which it does not always pay to take to Boston. All departments of the immense iron works at Boonton resumed work on Monday. For the last two months only tho blast furnace has been in operation ; the puddling furnaces, nail factory, keg factory, &c, being closed. The number of hands, when these works are in full blast, is something over 500. The Fall River Mills, 9,000 spindles, at Providence, is running full timo on print cloths. So is the Anawan Mill, also 9,000 spindles, making print cloths. These mills have been running full time for a month or more. Tho Metacomet is also running full time. The iron works of Cresson, Stuart & Peterson, at Philadelphia, have renewed operations, employing 170 hands. The number of workmen will be increased in a few days to 325.