POPULAR MISCELLANY. 



567 



likely to synchronize in their motion. If 

 such parts of a building must of necessity 

 be joined, let them be so joined that the 

 connecting link will force them to vibrate 

 as a whole, and yet resist fracture. Brick 

 chimneys in contact with the framing of a 

 wooden roof are apt to be shorn off at the 

 point where they pass through the roof. 

 Light archways connecting heavy piers will 

 be cracked at the crown. To obviate de- 

 struction from these causes, a system of 

 building may be adopted which essentially 

 consists of tying the building together at 

 each floor with iron and steel tie-rods, cross- 

 ing each other from back to front and from 

 side to side. The center of inertia of a 

 building, and of its parts, should be kept as 

 low as possible. Heavy tops to chimneys, 

 heavy coping;?, and balustrades on walls and 

 towers, heavy roofs and the like, are all of 

 serious danger to the portion of the struct- 

 ure by which they are supported. TMien 

 the lower part of a building is moved, the 

 upper part, by its inertia, tends to remain 

 behind, and serious fractures often result. 



Potelinet — The plastic substance, potc- 

 line, introduced by M. Potel, is formed of a 

 mixture of gelatine, glycerine, and tannin, to 

 which may be added sulphate of baryta, or 

 zinc-white ; and the whole may be colored, 

 if desired, with vegetable colors. Poteline 

 is molded while still hot ; and, when it has 

 become cool, yields itself to every kind of 

 manipulation. It can be turned, filed, bored, 

 or screwed, and it is susceptible of a very 

 fine polish, which may be conveyed by 

 pressure. This facility of working permits 

 it to be treated in the same way as bronze, 

 and makes it adaptable for all kinds of 

 mountings. It can also be used to seal 

 bottles and jars hermetically, for the fab- 

 rication of dolls' heads that can not be 

 broken, and for the composition of an arti- 

 ficial marble out of which ink-stands, door- 

 knobs, and a thousand other articles can be 

 made cheaply. The proportion of the dif- 

 ferent materials entering into the composi- 

 tion of this substance varies according to the 

 use that is to be made of it. For sealing 

 bottles, it should be used in a nearly liquid 

 condition ; for the manufacture of fancy 

 articles, in an opaque form ; while the ex- 

 act composition of the marble-poteline is a 



secret known only to the inventor. M. Po- 

 tel has described a method by which he 

 uses poteline as an envelope, to stop and 

 prevent fermentation and insure the pres- 

 ervation of fruits and meats. 



Oyster-CnltureiiiCoimecticat. — Accord- 

 ing to the last report of the Shell-fish Com- 

 missioners of the State of Connecticut, the 

 policy of farming out the oyster-grounds to 

 individual proprietor -cultivators has been 

 very successful. The number of persons 

 engaged in the business increased ten per 

 cent during the seven months covered by 

 the report ; and the rapid development of 

 the oyster industry is further shown in the 

 continued extension of the area of grounds 

 devoted to it, and in the increase in the 

 number of oyster-steamers. It has been 

 found that with reasonable care and labor 

 the number of star-fish may be so reduced 

 that those enemies shall be incapable of 

 doing serious damage to the oyster-beds. A 

 new enemy, however, threatens the beds, in 

 the shape of a sand-tube-building worm, 

 whose structures cause accumulations that 

 suffocate the oysters ; but the estimates are 

 contradictory as to the amount of the dam- 

 age it is likely to do. Efforts have been 

 made during the past year, with much suc- 

 cess, to redeem muddy grounds and make 

 them available for oyster-cultivation by cov- 

 ering them with shells and pebbles brought 

 from the Housatonic River. The demand, 

 both for oysters and for seed-oysters, is 

 constantly increasing, and it is not likely 

 that the supply will soon go ahead of it. 



What is a Real Forest ?— In all forest- 

 culture, says Mr. M. C. Read, in a paper on 

 " The Preservation of Forests on the Head- 

 Watcrs of Streams," which is published by 

 the Department of Agriculture in "Special 

 Report Xo. 5," "it should be remembered 

 that, for climatic purposes, an orchard ol 

 trees is not a forest. The planting of trees 

 along the highways, about our homes, in 

 parks and groves, ought to be encouraged 

 for a variety of reasons, but will have little 

 of the climatic effect of true forests. A 

 dense growth of underbrush, herbaceous 

 plants, and mosses under the larger trees, 

 which will retain the fallen leaves in place, 

 fill the surface-soil with rootlets, checking 



