Several circumstances are known under which rings or crowns are produced. (1) For example, in the spontaneous combustion of phosphureted hydrogen, the resulting white vapors of phosphuric acid rise, and roll round in horizontal white crowns when the air is calm (Fig. 4). These crowns, whose diameter keeps on increasing, end by separating into strips that dissolve in the humidity of the air. (2) The crowns that we sometimes observe in calm weather around cannons at the moment of firing have the same origin, although they are of a different nature, and spread horizontally to a certain distance. With vertical howitzers the crowns are horizontal, and very beautiful when seen from beneath, since they rise vertically. (3) As well known, a cardboard box having two apertures in the center of two opposite sides, when filled with smoke and struck upon one of these sides, allows the escape through the opposite aperture of curling rings of smoke. (4) Steam escaping into the open air, through the intermittence of a vertical eduction pipe, sometimes makes its exit in the form of circular or elliptical crowns.--_La Nature._ AN IMPROVED HYACINTH GLASS. The hyacinth is a native of the East. When it was introduced into England, in 1596, only four varieties of it were known, but the Dutch gardeners soon made wonderful progress in its culture, and, along toward the end of the sixteenth century, had produced at least two thousand varieties. This plant is well adapted for house decoration in winter, when flowers are rare. Its culture requires but little care. When the bulbs have taken root in a dark place they are gradually brought into the light, and placed where the temperature is moderate. [Illustration: FIG. 1.--HYACINTH GLASS. FIG. 2.--DETAILS.] Is a regular changing of the water favorable to the development of this plant? Many florists doubt it, and it is often recommended not to change the water, but only to replace that which has been lost through evaporation. Others are of a contrary opinion, and assert that the less favorable results that are obtained when the water is changed are merely due the fact that the roots are injured when the plant is taken out of the glass. With the old style of glasses it has always been difficult to renew the water regularly and keep the glass clean, but this inconvenience has disappeared in the glasses invented by Mr. J. C. Schmidt, of Erfurth. Fig. 1 represents one of these glasses, and Fig. 2 shows the details. As may be seen, the tube, a, which contains the bulb, may be removed from the glass, b, without the plant being touched or its roots disturbed. The glass, b, may thus be easily cleaned and filled with fresh water as often as necessary.--_Science et Nature_. THE BOTANICAL CLUB OF THE AMERICAN ASSOCIATION.