18. The identity of the tide-wave and the great wave of transla tion, shows the nature of certain variations in the establishment of ports situated on tidal rivers. Any change in the depth of the rivers produces a corresponding change between the moon's transit and the high water immediately succeeding. It appears from the observations in this report. that the mean time of high water has been rendered 37 minutes earlier than formerly, by deepening a portion of about 12 miles in the channel of a tidal river, so that a tide-wave which formerly travelled at the rate of 10 miles an hour, now travels at the rate of nearly 15 miles an hour.
19. It also appears that a large wave, or a wave of high water of spring tides, travels faster than a wave of high water of neap tides, showing that there is a variation on the establishment, or on the interval between the moon's transit and the succeeding high water, duo to the depth of the fluid at high water, and which should, of course, enter as an element into the calculation of tide tables for an inland port on the sea shore. The variation of the interval will vary with the square root of mean depth of the channel at high water.
" These results give us principles," the committee on waves conclude, "1, for the construction of canals; 2, for the navigation of annals; 3, for the improvement of tidal rivers; 4, for the navigation of tidal rivers ; .5, for the improvement of tide tables." But an equally valuable application, not however foreseen when these results had been obtained and examined, unless by Mr. Russell himself, was to the improvement of naval architecture. Of this, a brief account has already been given in the article Sistr-Dustnixo.
After the publication of the report by the committee on waves, which contained the experimental investigation of which we have now given the principal results, the phenomena of waves engaged the attention of eminent mathematicians, who endeavoured to deduce from first principles the curious facts which Mr. Scott Russell and his associates had observed, so as to reconcile theory with experiment. Among these were the Astronomer-Royal (a summary of whose con clusions has been given in this article), Mr. Green, and Professor Expand, who also succeeded in obtaining from analysis many of the very singular experimental results. Their researches were published in the Transactions of the Cambridge Philosophical Society, and those of the Royal Society of Edinburgh ; and Professor Kellam] also gave a view of the actual state to which the theory of waves had been brought in the Ileport of the tenth meeting of the British Association.
The theory of waves, regarded as forming a part of abstract mechanics, as well as in certain applications, has been considered also in the articles ACOUSTICS; INTERFERENCE ; VIBRATION; and UNDULA TORY Tneonv or LICHT. An excellent familiar explanation of the subject, especially as regards the coincidence and interference of waves, will be found In l'rofessor Tyndall's ' Glaciers of the Alps,' pp. 230-233.
WAX. There are several varieties of this substance, but the term used by itself means Bees' WAX, under which heading will be found an account of the manner in which it is secreted, its chemical con stitution, and the means employed in preparing it for commercial purposes.
Wax is used to a considerable extent in the making of candles cerates, ointments, and plasters. The so-called sealing-wax has no we:: in its composition. [SEesueG-WAX.] Spurious wax is sometime
made and sold for cheap purposes ; consisting of yellow resin, mutter suet, and palm oil, or turmeric instead of palm oil. Etching-was h made of bees'-wax and linseed oil; or white wax, gum benzoin, anc linseed oil; or white wax, Burgundy pitch, and powdered asphaltum Modelling-wax is described under Wax-3Ioommisso.
Vegetable War. Various plants yield a substance like wax, which is obtained, like the vegetable butter, by bruising and boiling them in water, when the wax, melting, floats to the surface, and there concrete. on cooling. Of these the most remarkable instance is the Ceroxylon the Wax Palm (Palma de Cera of the American Spaniards), Myriea Gale, Candleberry Myrtle, or Sweet Gale, a native of this country, yields a substance resembling bees'-wax when its catkins or cones are boiled in water. Myrica a native of North America, yields a similar substance when its berries are thus boiled : candles are made of it also, whence the plant is commonly called Tallow-shrub or Candleberry-tree. M. guerrifolia, a native of the Cape of Good Hope, is another species which yields a vegetable wax. It grows alorig the coast, on dry sandy plains exposed to the sea-air, where hardly any other plants will vegetate. The wax invests the berries in the form of a rough crust, which is separated by means of boiling water. It is of a greenish colour, but may be bleached. When made into candles it gives a very fine light. A vegetable wax is also obtained in China from Ligustrum lueidum, which is frequently mentioned as the wax tree in Dr. Abel's and other travels.
Japan is now known to be the chief country whence vegetable wax is imported. Small parcels have been brought to market for many years past ; the wax being at first in the form of small thin oval cakes stamped with Japanese characters. Afterwards it came over in cases containing 130lbe. each. In 1859 a cargo arrived direct from Nagasaki, in Japan, of nearly 9000 cases. It commanded a ready sale at the price of the best Russian tallow at that time, (57s. per cwt.), but went off slowly at the required price of 70s.
Dr. 31'Gowan, in a paper read before the Society of Arts in 1860, on the productive industry of Japan, said :—" One of the most remarkable products is the vegetable was, several cargoes of which have already arrived in this country from Japan. It is said that the first adven turer in this article sold his cargo at 100 per cent. profit. The Japanese, having discovered this wax to be a valuable article of commerce, seemed, when I was in the country, to be making arrangements for cultivating more largely the trees producing the berries from which the wax is expressed; and, with improved machinery, this article could, no doubt, be produced more abundantly and more cheaply. The product requires protracted bleaching before it arrives at the white state in which it is sent to our markets." Many other plants yield a substance similar to vegetable wax, some from the stem, but mostly from the berries. The Rhus a plant of the same species as the sumach, might (it has been suggested) be profitably cultivated in Australia or at the Cape of Good Ilope. It yields a wax residue, in quality between bees'-wax and vegetable tallow, softer and fatter than bees'-wax, and easily kneaded. It has already come into use in England in the candle manufacture. If combined with any cheap tallow or fat, it makes a mixture useful for many purposes.