454 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



Mr. Reid exhibited a piece of pure white flint, and inquired if it was very 

 abundant in this country. 



Dr. R. P. Stevens. — In Lee, Massucliusctts, there are immense quanti- 

 ties. Flint is quartz, and has a granuhited fracture, so has limestone, Can- 

 nel coal and other minerals. 



Transmitting Heat by Mercury. 



Mr. Johnson made a diagram on the blackboard of an experiment he had 

 tried with a stove having a non-conducting jacket and a coil inside of 27 

 feet, containing 45 pounds of mercury. As soon as the fire is kindled the 

 mercury expands and circulates, discharging its heat very rapidly. He 

 said with four pounds of coal he could boil four and a half pounds of water. 

 Mercury has the lowest capacity for heat, and the property of discharging 

 it very rapidly. He was never able, with all the fire, to get one turn or 

 two feet of the coil to show boiling. He measured the temperature by 

 color, according to the known rule in temperir.g steel. He had never heard 

 that such an apparatus, as circulating mercury, had ever been tried before. 



The Chairman. — There would be some difficulty if not danger in using 

 this system for heating, as mercury boils at 600 degrees. 



The subject for the evening, "Novelties at the Fair," continued from, 

 the last meeting, was here taken up. 



Single Thread Sewing Machine. 



Mr. James Wilcox, of the firm of Wilcox & Gibbs, exhibited their twisted 

 loop stitch family sewing machine. Mr, W. operated the machine, and 

 distributed several specimens of the work it done. He said: 



The great importance of the sewing machine in its h^-gienic not less than 

 its commercial aspect, is now generally conceded, that it is deemed super- 

 fluous to occupy time in discussing that part of the subject. In this coun- 

 try, where early attention was given to their adaptation to household pur- 

 poses, sewing machines are now scattered throughout the length and 

 breadth of the land, not only in stores, shops and manufactories, where the 

 competition of trade compels their use, but in private families of every 

 degree. Many persons who can ill afford the outlay, wisely consider it is 

 better to do without articles of ornament or luxury, than one that does 

 away with that torment of every household, the family sewing. As the 

 twisted loop stitch and the manner of making it is peculiar, I will endeavor 

 to explain it. 



The needle enters the cloth, and as it commences its retraction, the nose 

 of the hook enters the new loop brought down by the needle, which the 

 former loop had previously spread or opened ; the hook next advances, car- 

 rying the new loop through the old one, which latter still remains on the 

 looper or the inner portion of the back of the let off, the hook next moves 

 so as to rest against the lip, which latter is nearly drawn up, travels out 

 of the old loop to act in like manner upnn the new one, in its turn. The 

 twist given to the thread in forming the loop, has an important influence 

 in strengthening the hold of the thread in the cloth, and also on the beauty 

 of the stitch on the under side ; it will readily be perceived that with a 

 short stitch the seam will be much firmer than if made by the ordinary 



