CONSUMPTION. 343 CONTAGIOUS DISEASES. Principles of Economics (London, 1890-91), in which consumption or demand is given the first place in the discussion. The analysis of the forces whicii awaken the demand for goods, thus giving direction to the national production, has given rise to many new views in economies, and lias reopened the diseussion of fundamental prin- ciples. Such a developnu'nt corresponds to the actual development of modern life in which the rapid strides of physical and mechanical science ieem to have throwii for the time being questions of the limitations of human powers In' physical conditions into the background. See Exchange; POUTICAL ECOXOJIY : PKOOrCTIOX. CONSUMPTION. See Tlbeeculosis. CONTACT (Lat. contact us, from contingere, to touch, from com-, together -- tamjcrc, to touch). In geometry, two lines of which one at least is curved are said to be in contact when they have two or more consecutive points in common. E.g. in analytic geometry a tangent is said to be in contact with a circle in two consecu- tive points. This is called contact of the first order. If two curves have contact at three con- secutive points, the contact is said to be of the second order, and so on ; e.g. the curves y ^ x' and 1/ = .3*° — 3x -J- 1 have contact of the second order. The analytic condition for contact of the first order at point x = a. between two curves, yi = 0(*), ;/, = ^f). is that <t,
= ^(u («)' -.=.
){a), <p' and i/-' being the lirst derivatives. The condition for contact of the second order is that <p{a)^^{a). (p'i(f ^:f {(i),<p"ia)=:p" (ii). Contact of the third order requires the derivative of the third order, and so on. In contact of the nth order between two surfaees, there must be ( « -|- 1 ) consecutive common points. CONTACT-ACTION, Chemical. See Cata- LTTic Action : TiEactiox. CONTACT DEPOSITS. See Ore Deposits. CONTAGION (Lat. contayio, contact, from contingere, to touch, fiora com-, together ^- (an- gere, to touch). The communication of a dis- ease from the sick to the healthy, either by di- rect contact of a part alfected with the disease, or by indirect contact through the medium of the excretions and exhalations of the body. Among the contagious diseases are measles, scar- let fever, smalljiox, erysipelas, typhus fever, bu- bonic plague, epidemic influenza (the gi-ippe), diphtheria, and tuberculosis. See Bacteria; Epidejitc; Infection. CONTAGIOUS DISEASES. The law takes cognizance of contagious and infectious dis- eases as they menace the public health, for the protection of which health and quarantine laws are enacted under the broad authority of the police power of the State. (See Police Power.) For purposes of administration, this power may be delegated to municipal corpora- tions or like political suljdivisions. While the right to take summary measures for the public safety is one of the most ancient of government prescriptions and is rarely chal- lenged, yet it is none the less formidable, involv- ing as it does the power of the State forcibly to confine those suflTering from infectious diseases, een where properly cared for by friends or relatives, and other like interference with the personal rights of Iil)erty and property. Mari- time quarantine was early practiced by the com- n.crcial nations, and was enforced by the Vene- tians in the fifteenth century; but municipal health regulation is of somewhat later develop- ment, and the two are still usually separated in administration. Thus, for instance, the Board of irealth of the City of New York exercises jurisdiction within the city proper and upon the waters of the bay to the limits of quarantine, which, with its shipping, is under the antluu-ity of the Board of Quaranlino Commissioners and the health officer of the port. In the United States the enactment of quarantine laws is held to be among the powers preserved to the States under the Constitution. I'nder their authority, however. State boards of health are created and general statutes passed delegating the power to local boards in cities, towns, and villages. In the larger cities this power is usually conferred separately by provision in their cliartcr or act of incorporation. The public health laws of the several States arc similar in charact<'r, and may be consulted for details. Violations of the sanitary code are usually made misdeme.aiiors. and pun- ished by imprisonment or fines. For the purpose of avoiding any questions that might arise from the possible interference of local regulations of the public health with the Federal prerogative of regulating interstate commerce. Congress early passed acts adopting such State laws and re- quiring their observance by Federal officials (act of February 25, 1799: act of April 29, 1878 [20 Stat. L. 37']). In 1879 a National Board of Health was created, but its powers were little more than advisory, and bv the act of Congress, February 25, 1893 (27 Stat. L. 449), it was abolished and its powers and duties transferred to the ilarine Hospital Service, which, under the direction of the Secretary of the Treasury, performs the functions of national quarantine. Questions pertaining to the people at large aris- ing from immigration and importation belong to Federal jurisdiction as incidental to the consti- tutional right of regulating commerce. Thus conditions of entry are imposed, .such as deten- tion, inspection, and disinfection, and under the act of 1893 protective restrictions may even be laid upon interstate intercourse where a danger is threatened and State autliority is wanting or lax. The Federal quarantine may arrest the entrance of forbidden persons or things ; but once past the 'Barge Office' or custom-house, the local authorities take jurisdiction. Naval ves- sels as well as commercial are bound to observe quarantine rules. In Great Britain a similar system of sanitary protection prevails. In England, the controlling statute, the Public Health Act (38 and 39 Vict, c. 55 [1875]), is compiehensive in its provisions and regulations, though it does not extend to Scotland or Ireland, or, except as to special pro- visions, to the city of London. The Infectious Disease (Notification) Act (52 and 53 Vict. c. 72) and the Infectious Dise.ise (Prevention) Act (53 and 54 Vict. c. 34), as the titles signify, pro- vide respectively for the course to be pursued in notifying the proper authorities in cases of defined contagious illness, and the regulations to be adopted in the way of inspection and dis- infection to prevent infection. The first applies to the United Kingdom, and may be adopted by urban and rural authorities of ports and local districts: the second is confined to England. In its international aspect, the obligation rest-
