Page:The New International Encyclopædia 1st ed. v. 17.djvu/473

* SAILINGS. 433 SAINFOIN. the linos they cut in the phiiie of projection are straight lines. It is evident, therefore, that the straight line joining any two points on the chart is the projected great circle arc. The meridians and parallels of latitude being properly pro- jected on the chart, it is very easy to olitain the latitude and longitude of as many points of a great circle are as we wish. These points may be transferred to a Mercator chart and the courses between them obtained in the usual way, or they may be determined from the gnomonic chart itself, but this is usually unnecessary. The <levelopment of the gnomonic chart for use in great circle sailing is due to the late Gustavo Herrle, chief draughtsnuin, and G. W. Little- hales, chief of the division of chart construction in the Hydrographic Office, United States Navy Department. Various other means of graphically solving great circle problems have been devised. Prob- ably the earliest was the 'great circle pro- tractor' of Prof. W. Chauvenet, United States Navy. About the same time Jlr. Stephen JIartin Saxby of the British Navy designed a very simi- lar instrument, which was called the spherograpb. Capt. C. D. Sigsbee, United States Navy, designed •a great circle protractor many years later, and recently devised a new form of it which is now issued by the Hvdrographic Office of tlie United States Navy. All of these inventions utilize the stcreographic projection of a hemisphere in which the meridians and parallels of latitude are shown. The spherograpb consists of a card upon which is the stereographic projection of a hemisphere with the meridians and parallels of latitude drawn and marked. Over this, and pivoted by a pin upon the same centre, there is an e.xactl.y similar projection of a hemisphere upon a trans- parent disk. All the meridians are great circles; therefore, if we consider the bounding meridian ■of the lower projection as that of the place of departure and mark the point upon it at the proper latitude, it is very easy to obtain the great circle leading to any other point as fol- lows: Turn the transparent disk until its pole ialls upon the marked point of departure. Every meridian of the transparent disk is now a great circle. If the point to be arrived at is marked on the lower disk in its proper latitude and longitude (reckoning the latter from the meridian ■of the point of departure), the meridian of tin? transparent disk which passes through it is the great circle connecting it with the point of de- parture. It is evident that this instrument is capable of graphically solving spherical triangles and other astronomical problems. Captain Sigsbee's protractor is simpler and perhaps slightly slower in operation for some problems, but it is more easily handled, less likely to be injured and made useless on board ship, and is larger and more accurate. It consists of a large sheet of heavy smooth paper or thin card- board upon which the hemisphere is stereograph- ically projected. The points of departure and arrival are marked upon this as in the sphero- grapb. In addition, upon a sheet of tracing paper, laid over the projection, you mark the centre, the point of departure, and the point of arrival. Turn the paper (keeping the centre al- ways over the lower one) until the point of ■departure falls on the pole. The meridian which passes through the point of arrival is the great circle. Trace such portion as you wish, turn the paper back to the (irst position, and pick up llie latitude and longituiie of as many points as you want. Captain Sigsbee's protractor readily lends itself to the graphical solution of a ver,v large number of astronomical problems. SAIL-LIZARD. A large t)riental li/.ani l/,o- phiirux AmliDiiicisis) allied to the frilled lizard (q.v.), sometimes a yard long, with a viTy com- pressed olive-green body and tail, the latter sur- mounted for half its length by a high, serrate crest, supported by spines from" the vertebra-. It is found from Java to the Philippines, dwells in THE SAIL-LIZARD. the jungle near streams, eats almost everything, and when frightened rushes into the water and endeavors to conceal itself on the bottom, where it can readily be taken by a net. Its llesh Ih sought for food. SAILOB'S CHOICE. A common and highly valued food-tisli (Oitliojirixlis cliri/soplvrus) along the sandy southeastern coast of the United States, belonging to the family of grunters bailor's cHoicK {LngodoD rhomboldea). (Haemulidie), called 'pigfishes' in this genus. The form is ovate-elliptical, and the length is 1'2 to 15 inches. The same name is given to several allied fishes, and especially to a small sparoid, or porg^' (Lafjodon rhomhoiilca). also called 'pin- fish.' a beautiful silvery-blue and gold fish of the Gulf ("oast. SAIN'FOIN (Fr. snin-foit, OF. also sninct foiii. siiintf<iin. from sniii. from Lat. ,s(Iiic(h.«, holy, less probably from Lat. saniis. sound -f- ^oiii. from Lat. fa'niim. hay), or Ksp. sKTTK {Onoltrn- c/ii.s' vicifFfolid). A perennial pink tlowered legu- minous plant, native to the temperate parts of Kurope and Western .sia. and widely cultivated in Europe for pasturage and hay, but little in the United States. The plant grows to from 1 to 2