A very important case has recently been tried before the U. S. Courts in this city, which we cannot pass over in silence. On the late voyage of the steamship Franklin, one of the firemen, when he left New York, was intoxicated, and when heated at his labor became stupid, disobeyed the command of the assistant engineer, fell off the stairs, became insensible, and in that state the said engineer poured some pails of cold water over him, after which, in a very short time, he was a corpse. The engineer was brought before the court on a charge of manslaughter, but the evidence, to our view, did not exhibit any intention to injure the deceased man. The evidence, however, developed a most heartless system, and brought to light the life of a steamship fireman, in comparison with which that ot the meanest serf is blessedness itself. It was stated that the firemen were generally intemperate, that they drank a great deal of spirits, and no wonder. The fire-room is below the water line of the ship, and is often at 80, 90, and 100 of temperature. The men have to work in this atmosphere, and sometimes they can scarcely breathe. Frequently they sink down exhausted, and by pouring water upon them, revive ; this was applied to the deceased fireman, but ha will wake no more till the last trump shall sound. The temperature ot the human body is 99 '5, and although it has Tjeen proven by many experiments, that the body maintains the same heat in the man who lives in the cold regions of 30 below zero, and him who lives in the tropical regions ol 90 above it, yet reason, common sense, and experience tell us that -there must be a certain temperature of the atmosphere most in harmony with the temperature of the body. Men have stood and may stand to live in an atmosphere of 100, (and we have entered into an atmosphere above 200) yet they can only do this for a short period. The difficulty of breathing (the fiery choking sensation) tells us that such an atmosphere cannot be breathed with impunity. For example, an atmosphere of 995—the same temperature as that of the human body—must be in equilibrium with it; now, as the action of the lungs is to promote slow combustion in the body, the atmosphere, to be perfectly healthy for a man, should always be colder than the carbonic acid gas and moisture from the lungs. Unless this is the case, the atmosphere, as it should, cannot act as a good condenser to the heat of the lungs, therefore, a highly heated atmosphere must be injurious to health; it cannot be otherwise. We have observed that those men and women whose lot was that of working in warm rooms for dressing fine muslins, in factories, in printworks, firemen of steamships, &c, presented a bleached and consumptive appearance, and it we had statistics of their health and longevity, we have no doubt but the bill of mortality and sickness would be appalling. The evidence presented by the engineers and firemen of the Franklin conclusively proves this, and something more is demanded in the inspection of steamships than an examination of the hull and boilers for the safety ot crew and passengers. The safety of the lives of firemen working away down in their minor pandemonium, demands the attention of all philanthropic men, and we hope that this case may lead to a better ventilation of boiler rooms on board steamships. The best temperature of atmosphere conducive to health ranges from 42 to 75 ; we have no statistics to prove this assertion, we only conclude that these atmospheric temperatures are the best, from a knowledge of their influence upon fermentation, and the robust forms and general health of the natives of those countries, the temperature of which averages about 50 throughout the year, and never rises 30 above nor 30 below that standard, excepting upon rare occasions. The natives of very cold climates are stunted specimens of the human family, and if some of the natives of Africa are tall and muscular, it is owing to a physical constitution of an entirely different character from that of the Caucasian race.— They would no doubt make excellent firemen in our present steamships, (only they would have to be more strictly watched than men of our own race,) but we believe that the temperature of the boiler room can be maintained at 65 or 70 without any loss of heat to the boilers, and the firemen thereby be enabled to work with safety and comfort