104: ANNUAL OF SCIENTIFIC DISCO VEEY. 



is easily remedied, for it can be very cheaply made incombustible with Blake's 

 paint, or with a paint made of common water lime, mixed with any cheap 

 oil ; or with the following cheap preparation. Slake good stone lime under 

 cover, with hot water, till it falls into a fine dry powder. Sift and mix six 

 quarts of lime with one quart of salt, hi two gallons of water, and boil and 

 skim off any impurities. Now to 5 gallons of this mixture add 1 Ib. of alum, 

 Ib. of copperas, and slowly, while boiling, Ib. of potash, and 4 quarts of 

 clean sharp sand, and afterwards any coloring matter desired, and apply the 

 mixture with a brush, as you would any paint, only thicker, and it forms a 

 strong surface, impenetrable to water, and incombustible from heat or sparks 

 that would ignite any ordinary wooden roof. 



The raiters for such a roof should be stiff, but may be made of stuff 1 in. 

 by 8 in., if well supported, and placed 6 feet apart, with ribs 1 in. by 2 in., set 

 edgewise, and well nailed to the rafters, not over 18 in. apart. The boards 

 may be thin, if well nailed to the ribs, but must be absolutely weh 1 seasoned, 

 and if put on and covered while hot from the kiln, ah 1 the better. One of the 

 advantages of such a roof is the ease with which it can be moved in after 

 years, either on the building, or by transferring it in sections to another, which 

 in ah 1 border towns is no small item of advantage. New York Tribune. 



INDUSTRIAL EESOUECES OF MASSACHUSETTS. 



The increase in the industrial resources of Massachusetts within the past 

 ten years is one of the most remarkable facts connected with the history of 

 our country during this period. When the industrial statistics of the State 

 were first collected, in 1837, they exhibited an annual production amounting 

 to $86,282,616. In 1845 the amount was $124,749,457. It has now swelled 

 to $295,820,681 an increase of one hundred and thirty-eight per cent, since 

 1845, and two hundred and forty-two sine* 1837 ; and this while the increase 

 of population has been only thirty-four per cent, since 1845, and sixty-two in 

 the longer period named. "And yet this result," says the Secretary, in his 

 report, "so surprising in itself, falls manifestly below the reality. Leaving out 

 of the account those branches which were unfortunately omitted in the specific 

 inquiries, and making all possible allowance for the greater accuracy attained 

 in the collection of the information embodied in the accompanying pages, it is 

 still apparent that the truth has not been reached. It is next to impossible 

 for the taxpayer, when called upon by the assessor to answer such questions 

 as were propounded under the law, to divest his mind of the impression of an 

 intimate connexion between his answers and the assessment of his taxes. 

 Hence the general tendency to understate results, and an absolute refusal in 

 numerous instances to answer at all. Had those branches which were over- 

 looked been included in the returns, and honest and truthful answers obtained 

 in all cases to the questions proposed, I am fully persuaded that instead of 

 two hundred and ninety-five millions, we should have had an aggregate of at 

 least three hundred and fifty millions, or considerably over one million of 

 dollars per day of every working day in the year. As it is, the result exhibits 

 a rapid and substantial growth in our industrial resources which is believed 

 to be without a parallel in the history of the world." 



