MECHANICS AND LSKFUL ARTS. 123 



end of nineteen hours the heat of the frame diminished ; yet, fourth, that at 

 the end of seventy hours the temperature was 69 still. This is a conclusive 

 answer to those who think that masses of heated water, or heated porous 

 materials, like rough stones, will become so reduced in temperature by a few 

 hours' withdrawal of the prime heating power, as to endanger the plants 

 cultivated in houses thus warmed. The experiment continued to be success- 

 ful, and enabled pineapples of the most perfect quality to ripen. 



ALLEN'S GRIST MILL. 



Mr. Z. Gr. Allen, of Buffalo, has recently constructed a superior mill, which 

 differs in many important respects from those now in use. The spindle, or 

 the upright shaft through the centre of the stone is continuous, being, by the 

 peculiar construction of the mill, made in one piece, instead of being divided 

 as usual in the middle : and the same being made adjustable laterally, both 

 at top and bottom, allows of much more perfect " tram" than is generally 

 attained. The method of connecting the stone with the spindle is far more per- 

 fect than any with which we are familiar being in fact a perfect universal 

 joint without possible slack. This is attained by slotting through the spindle 

 and inserting a flat, thin " driver," or bar of iron, edge uppermost, and con- 

 necting it by a tapering pin in the centre, and by suitable boxes at each 

 extremity. Each box being secured to the stone by a single bolt, the whole 

 is as conveniently removed, when necessary, as are the more primitive 

 arrangements. But the most conspicuous innovation is hi the holding down 

 of the stone which is done by a lever and weight resembling those attach- 

 ments to a safety valve. In all rapid grinding with light stones, it is common 

 to hold the grinding surfaces together by applying a screw to a lever pressing 

 upon the spindle, and, in the best device of this kind, this screw is so con- 

 nected that it is always worked to correspond with the elevations of the stone 

 by the ordinary " lighter screw." By that construction the upper centre is 

 depressed in proportion as the lower centre (and consequently the stone) is 

 lowered by the miller in the course of the work, and provided the adjustment 

 of all the parts is perfect, the operation of the mill is, in this respect, precisely 

 similar to the one under notice. But such perfection is rarely attainable hi 

 practice, and the spindle is liable in some positions to be either loose or so 

 tightly held as to become heated. Another obvious advantage of the new 

 arrangement is the liberty allowed to the stone to rise in case of dropping any 

 hard mass, as a nail, into the mill. In brief, the device under notice appears to 

 be a successful attempt to apply the most perfect of mechanism to the hanging 

 of mill stones, with the addition of a self-acting means of holding down the 

 stone without a possibility of ever exceeding the required degree of force. The 

 stone is as readily removed for picking as under the ordinary arrangements. 



TOBACCO PULP CIGARS. 



A patent has been taken out in England for reducing those parts of tobacco 

 leaves left after the finest portions are stripped off for cigars into pulp, by 

 cutting, them up in a machine, then submitting them to the action of steam in 

 a close vessel. After this the pulp is made into sheets, by passing it through 



