376 Miscellaneous Intelligence. 



a pressure equal to 1200 feet of water it began to swell, and with 

 1400 feet, or 600 lbs., on the square inch, it burst. When mea- 

 sured after the experiment, it was found to have swelled until of a 

 diameter of 1 \ of an inch. The edges of the fracture were not 

 ragged, but smooth and sharp like a knife. 



In a second experiment the pipe was two inches in diameter, 

 and one-fifth of an inch in thickness. It sustained a pressure 

 equal to that of a column of water 800 feet in height with hardly 

 any swelling, but with 1000 feet it burst. The fracture here 

 was not so fine as in the former pipe, the metal being much less 

 ductile. — Caledonian Mercury. 



3. Method of curing Smoky Chimneys. — There is a way of build- 

 ing a vent, which was found to succeed in the huts which were 

 erected by the British army in America during the war of the 

 revolution ; and even in the underground vents which were built 

 to their tents when out at a late period of autumn, or rather the 

 beginning of winter. In the writer's own house, where the principal 

 vents were altered upon this plan after the house was finished, and 

 in which there have been fires for nine months, the purity and 

 cleanliness of the rooms sufficiently testify its efficacy ; but he has 

 a still farther proof in the testimony borne to it by Mr. Elliot, who 

 built the house and made the alterations, and who was so con- 

 vinced of the improvement effected from what he saw, while the 

 vents were damp, that in the two houses which he has since built 

 in Melville-street, Edinburgh, he has constructed all the vents on 

 the same principle. The method is simply to contract the vent as 

 soon as possible, then gradually to widen it for 4 or 5 feet, and 

 then again contract it to the usual dimensions, and carry it up in 

 any direction. No register grates are necessary. — New Monthly 

 Mag. xv. 456. 



4. Suggested Improvements in light-houses. — Although great 

 improvements have of late years been made through the British 

 dominions upon light-houses, yet it is possible to make further 

 progress in so useful and necessary a building. They may be 

 so constructed as not only to ascertain the situation of head-land, 

 harbours, $-c. ; but also to determine the distance the observer may 

 be from them in the following manner, viz. — Suppose the light- 

 house to be erected of a conical form, the great light at the top 

 may have what tinge it shall be thought proper to give it ; under- 

 neath, at a distance of from 100 to 150 or 200 feet, three more 

 smaller lights to be seen a few leagues at sea. So long as these 

 last-mentioned are not seen, the observer may conclude he is a 

 considerable distance from the light-house ; but as soon as any 

 one of them is perceivable, he need only take the angle of altitude 

 between it and the great one, and in a table calculated on purpose 



