Join L. Hayes, Esq., editor of the Bulletin of the National Association of Wool Manufacturers, gives in an article published in the July number of that periodical, some interesting and important facts in regard to spontaneous ignition in woolen mills, a few of which we extract. Much has been said upon this subject, at various times, in the Scientific American, yet it is of so much importance, that any facts throwing light upon this source of conflagration, or calculated to put proprietors on their guard are always seasonable. The combustion of oily wool waste, says Mr. Hayes, is familiar to all older manufacturers; that the cases do not more frequently come under the eyes of manufacturers is due to the precautions now generally in use. Mr. Kingsbury, of Hartford, has informed me of two cases which came under his observation where spontaneous ignition had taken place in barrels of oily waste left accidentally in woolen mills. In both cases, the fires were extinguished without damage. Mr. Gould related to me this circumstance: Some years since a large quantity of what was called clean woolen waste, used in the manufacture of coarse satinets, had been brought from a woolen mill, and stored in a wool-house in Pearl street, Boston. The insurance companies having been informed of the fact, notified the party storing the waste to remove it, on pain of forfeiture of his insurance. Objection having been made to the fastidiousness of the insurance offices, Mr. Gould himself piled up portions of this waste in a yard at the rear of his office in State street. The waste was found to be very oily on handling. The pile was exposed in a damp warm day in August. In less than twenty-four hours the pile took fire spontaneously. Mr. Badderley, in his report on the fires of London for