Page:Popular Science Monthly Volume 40.djvu/885

Rh which, while it affords the best protection to the picture from moisture, is easily removed and renewed. A source of danger to pictures to which not enough attention has been given is that which arises from the development of moisture by chemical action within the substance of the painting itself. An old medium of remarkable qualities has been recently discovered, concerning which nothing more is said at present, till its qualities are proved. Apparently the most durable surface that can be produced with modern mediums is that obtained with a mixture of copal oil varnish and linseed oil; and, until the proper medium is discovered, the best we can do is to paint our pictures with this medium and a carefully selected group of pigments, and then, as a further precaution, coat the pictures, when thoroughly dry, with a layer of mastic dissolved in turps (or turpentine).

Illustration of Customs.—The Pitt Rivers collection in the University Museum at Oxford is designed to illustrate the customs, life, and religious observances of primitive and semi-civilized races. The contents are arranged with a view to showing the various stages of development among different races and at different times, and to establishing direct relationship between the primitive and the modern types. The collection has also many European objects of antiquarian interest. Among them are specimens of the hornpipe, the instrument that gave its name to the dance performed to its music, and of the pipe and tambour used by the mummers at their performances. Among the exhibits relating to savage races is a collection of masks from Fiji, New Britain, and elsewhere, such as were worn at funerals by the male relatives of the deceased. In some cases the very skull of the dead man was made into masks, with the idea that he should assist at his own obsequies. The jew's-harp in many forms and developments—none, however, dating beyond the sixteenth century—has a place in the museum, together with a collection of primitive reed instruments, some of which were blown by the mouth and others by the nostrils. Of fire-kindling apparatus, the frictional fire-sticks of savages, the rather elaborate mechanical contrivance of the Brahman priests, and the apparatus used by the Vestal Virgins to kindle the sacred lamp if it should be extinguished, are shown,

Mediæval Guilds.—According to a paper in the Archæological Institute by the Rev. J. Hirst, on the Guilds of the Anglo-Saxon Monasteries, a regular system of communication was kept up between the various religious houses by means of messengers, who, being men of the world, were able to supply the news of passing events, even in the most distant countries. Other visitors to the abbeys were pilgrims, who were often admitted as brothers, and were thus enabled to participate in the benefits derived from the prayers of the community. From these sources no doubt the monkish chroniclers derived much of their information, which they so carefully recorded. The author said these ancient guilds threw a light on the origin, rapid increase, and organization of the EngishEnglish [sic] trade-guilds at a later period. Mr. J. T Micklethwaite pointed out a difference between these two sorts of guilds. The trade-guilds kept a common purse, whereas those attached to the monasteries did not; the absence also of the word guild in the Saxon manuscripts led him to believe that the trade-guilds were not derived from the monastic ones.

Spiders as Marplots.—A curious account is given in Engineering of the way in which the accuracy of engineering work is often impaired by spiders and their webs. When plumb lines are sunk in shafts, the spiders sometimes attach their webs to them and draw them to one side. The accuracy of a certain work in the Hoosac Tunnel was destroyed until the lines, 1,028 feet long, were inclosed in cases. It has been suggested as a remedy to apply electricity to the lines so as to burn off the spider-threads. The writer in Engineering once found his vision when using the level distorted by the appearance of curved lines in its field. After consulting an oculist and paying his fees, he discovered that the whole trouble was caused by a little spider which had settled itself in the eye-glass of the telescope of the level. An electric light metre, of the revolving fan type, was found doing imperfect work, as it recorded only a small fraction of the electricity that was known to be used. It was found that