EXPECTATION. 371 EXPERT. by means of our ready-signal. Since, however, we are making a scries of tests, mid the series i9 progressing in a known direction (from one- ness toward twoness), the observer can hardly remain unprejudiced; at each fresh step of the series lie will think, "This time there must be two!" The judgment 'two' will, therefore, come too soon; our result is vitiated by the error of expectation. In all such eases sonic method must be devised whereby this error may be eliminated. In the present instance we eliminate it, very simply, by reversing our series. We begin a second set of tests with a separation of the compass points that gives two clear pressures, and work down, step by step, until 'two' passes over into 'one.' The 'one' comes as much too soon, in this reversed series, as the 'two' came too soon in the preceding series. By averaging the results of the two series, we rule out the ex- pectation error. Consult: Wundt, Outlines of Psychology (Eng. trans., Leipzig, 1898) ; Killpe, Outlines of Psychology (Eng. trans., London, 1895) ; Titche- ner, Primer of Psychology (New York, 1900) ; id., Experimental Psychology (New York, 1901). See Fatigue ; Habit ; Practice ; Psychophysics. EXPECTATION WEEK. A name some- times given to the period between Ascension Day and Whitsunday, because during this time the Apostles continued praying in earnest expecta- tion of the Comforter. EXPECTORANT (from Lat. expectorare, to drive from the breast, from ex, out + pectus, breast). Any medicine given to carry off the secretions of the respiratory tract. ( See Bron- CHTJS; Bronchitis.) The principal expectorants are antimony, squill, ipecacuanha, senega, balsam of tolu, lobelia, gum ammoniac, asafoetida, and galbanum. EXPECTORATION. The act of spitting; also the sputum, which is the Latin name for the mucus or other secretion discharged from the air- passages. The examination of expectoration is of the utmost value in the diagnosis of diseases of the chest. Often the nature of an ailment can be determined or the diagnosis confirmed by the examination of the expectoration. In simple bronchitis the sputum is frothy and colorless, and floats on water. In chronic bronchitis it is generally yellowish or greenish, and, owing to an admixture of pus, it sinks in water. If the sputum be tinged with dark blood, pneumonia is suspected. In tuberculosis of the lungs bright blood may be coughed up, or mucus of a very pink tint from the coloring matter of blood, or the sputum may be very abundant, viscid, green- ish, and partially submerged in water. It may be offensive in odor during tuberculosis, and is always so during gangrene of the lung. But the diagnosis does not rest on the appearance of the sputum or the examination of the chest. Methods of staining certain elements and the use of the microscope will decide upon the presence or absence of the tubercular bacillus ; Pfeiffer's bacillus, of In grippe; the pneumococcus and the pneumobacillus, of pneumonia ; streptococcus, of pus infection; or other bacilli, as well as elastic fibres from the lung. In certain cases expectora- tion of mucus is to be encouraged, and cough must not be cheeked. In all cases of known or suspected communicable disease, as influenza {la grippe), pneumonia, or tuberculosis, sputum must be received in a vessel in which it is kept moist till it is destroyed by disinfection with a I to 40 solution of carbolic acid j "i better, re- ceived in a paper spit-cup which i burned before it is dry. Carpets, furniture, and bedding should be protected from expectoration in the e ca es of disease, and sheets, pillow cases, handkerchiefs, napkins, and night clothing should in- frequently changed and dipped in boiling water In-fore being washed. EX PE'DE HER'CULEM (Lat., Hercules from his foot). A Latin proverb, meaning that the whole can be tested by a part. The saying is assigned to Pythagoras, and is paralleled by another similar phrase, ex ungue leonem, 'You can judge of a lion by his (law.' EXPERIENCE MEETING. A nana' applied to religious gatherings at which one or more of those present set forth their spiritual history and experiences. In the Methodist Church they are called class-meetings, and a g some other de- nominations covenant or conference meetings. The ordinary prayer-meeting of a church some- times takes this form. Such passages as Mai. iii. 16 and Col. iii. 16 are quoted in defense of meetings of this kind. EXPERIMENTAL PSYCHOLOGY. See Psychology, Experimental. EXPERT (Lat. expertus, skilled, p.p. of ex- periri, to test). One who is specially experienced in a particular subject-matter of inquiry, as the result of previous habit or practice or study. From the legal point of view, the most important function of the expert is that of witness in liti- gated cases. The earliest recorded appearance of the expert in English judicial tribunals was in the capacity of an adviser of the court. As early as 1353 we are told that, in an appeal of mayhem, the sheriff was ordered to summon skillful surgeons from London to inform the court whether the wound in question was mayhem or not. In the seven- teenth century it became customary to call ex- perts as helpers of the jury. When acting in this capacity they were sworn and examined by counsel as witnesses. At the trial of the Suffolk witches, in 1065. Sir Thomas Browne, the physi- cian and natural philosopher, testified, after ex- amining the accused, that he was of the opinion that they were bewitched. From that time the medical expert has been an important figure in criminal trials. But expert testimony is not con- fined to members of the learned profession. It may be given by farmers, mechanics, brokers, lumbermen, physicians, clergymen, scientists, lawyers, or any person qualified by special train- ing and knowledge to answer questions requiring such training and knowledge to answer them. (See Evidence.) When the case is before a court and jury, it is for the court to say whether the questions call for expert assistance, as well as whether a particular witness j s jus- tified to speak as an expert thereon. It is for the jury to determine the worth of an expert opinion, after it has been given. Such opinion (however famous or learned or experienced the one who utters it may be) is not binding upon the jury. It may be accepted as helpful, or it may be totally disregarded. At times the ex- pert deposes to facts rather than opinions : as when a chemist explains the examination of an alleged blood-stain, or of parts of a human bodv.
