At present, San Francisco is a city of about thirty thousand inhabitants, and in spite of the repeated visitations of the calamity of destructive fire, it has suffered no stoppage in its rapid progress. On the contrary, these fires seem to give a new impulse to the energy and enterprise of its inhabitants, and, by impressing upon them the utility of building their houses and stores of the more substantial brick, to have been of permanent benefit. Like the water of a rapid river, which, meeting with a serious obstacle in its course, is checked for the moment and then, having gathered new strength, surmounts the barrier and springs forward with renewed energy, San Francisco has pursued her course. The late fire, decidedly the most disastrous the new city has experienced, produced for awhile a general stand in business. But the go-aheadative principle was too strong for a continuance of a stagnation; and all the sufferers set about doing their utmost to retrieve their fortunes. Success must wait upon such persevering energy. Sacramento City is fast treading upon the heels of her commercial sister city. Improvements are constantly being made to the appearance of the city and the comfort of its inhabitants. A levee is in course of construction, which, it is thought, will effectually protect the city from being flooded during the season of the rise of the river. The overland emigration of which Sacramento is the goal, contributes to swell the population rapidly; and, during the rainy season the greater portion of the population of the northern mines flock into the city for refuge till the digging season commences. Stockton, Benicia, San José, and Sutter are each increasing the number of their residents and their trade very fast. The first is the depot of the southern mines; the second, the military and naval station, chosen by the government officers; the third is the capital of the State; the last is a thriving town, near Sacramento, but in a better situation.