Page:Collier's New Encyclopedia v. 10.djvu/554

YEAST lord of the fee. It was abolished by the Felony Act, 1870. Year of grace, any year of the Christian era. Year to year tenancy, in law, a tenancy taken at first for a year, but which continues for a second year unless one of the parties on the expiration of the first six months intimates to the other his intention not to renew it. The same rule will obtain year after year till the six months notice of non-renewal is given.  YEAST, the yellow substance, having an acid reaction, produced during the vinous fermentation of saccharine fluids, rising to the surface, when the temperature of the fluid is high, in the form of a frothy, flocculent, viscid matter (surface yeast), and falling to the bottom (sediment yeast) when the temperature is low.  YEATS, WILLIAM BUTLER, an Irish poet; born in Dublin, Ireland, June 13, 1865. He wrote: "The Wanderings of Oisin" (1889); "John Sherman" (1893); "The Countess Kathleen" (1892); "A Book of Irish Verse" (1895); "The Secret Rose" (1897); "The Wind Among the Reeds" (1899); "Reveries from Childhood and Youth" (1916).  YELL, the second largest of the Shetland Islands; separated from the mainland by Yell Sound; 25 miles N. of Lerwick. It is about 17½ miles in length, and from half a mile to 6 miles in breadth. The surface is chiefly moorland, and fishing is the leading employment.  YELLOW FEVER, an infectious continued fever, ushered in with languor, chilliness, and more or less severe lumbar pains and frontal headache, countenance flushed, eyes at first humid, then suffused, and ultimately ferretty, skin imparting a tingling heat to the touch, and, as the second stage advances, gradually acquiring a lemon or greenish-yellow tinge, mind usually disturbed with hallucinations, or more or less violent delirium, restless watchfulness, or, possibly, drowsiness even to extreme coma, epigastric uneasiness, spontaneous vomiting without effort, first of a clear glairy fluid, but subsequently with coffee-ground flocculi, or blood itself, often, toward the close, with irrepressible hiccough, and vnld shrieking or melancholy wailing, tendency fatal, but the disease generally confers an immunity from subsequent attacks.

The first recorded outbreak of yellow fever occurred in the West Indies in 1647, and since that time it has been recurring at regular intervals in an epidemic form, and gradually extending its range; but it is endemic in certain localities, and notably so in the islands of St. Thomas and Santo Domingo. Regarding its altitudinal and horizontal ranges Dr. Macdonald says: "It may be very well to assign an altitudinal limit of the spread of yellow fever, and, roughly speaking, this may be estimated at between 2,000 and 3,000 feet above the level of the sea, but the local conditions of every country seem to determine a range peculiar to itself. Thus the disease has been known at Newcastle, Jamaica, at an elevation of 4,000 feet, while in the valley of the Mississippi its highest recorded range is about 600 feet (admitting the fever of Gallipolis to be of the genuine type). Humboldt alludes to the farm of Encero, in Mexico, at an elevation of 3,243 feet, as the altitudinal limit of the black vomit. At Santo Domingo the encampments of the French in 1792 and of the English in 1796 enjoyed an immunity from the disease, while it was spread far and wide among the troops in the low country. Though the West Indian Islands, and the neighboring coasts of North and South America, may be looked on as the focal area of yellow fever, yet, taking the outlying points at which its occurrence in the epidemic form has been recorded, its geographical range must be regarded as very considerable indeed, i. e., between lon. 97° W. and 2° E., and between lat. 48° N. and 35° S. At least for the space of a century and a half, up to the year 1850, the Amazon river, dividing the Brazils from Guiana, limited the extension of yellow fever S. of the line; and while the disease was raging at Rio and Bahia, at the close of that epoch, the Montevideans flattered themselves that they were without the geographical limits of the pestilence, till it fell to their turn to sustain its visitation several years later, when the illusion was dispelled. Similar facts may be adduced regarding the extension of the disease along the shores of the Pacific; so that, however well we may be acquainted with its present range, making all due allowance for temperature, we cannot tell what the future may bring forth. In this connection it may be mentioned that a temperature of at least 72° is assumed to be essential to the development of yellow fever, though cases exceptional to this rule may now and then happen. Yellow fever is communicated from one person to another only by a species of house mosquito (Stegomyia fasciata). As a result of this knowledge it was entirely eliminated from the Panama Canal zone, and from other tropical areas, including Havana.

In December, 1878, a board of experts,