278 



THE POPULAR SCIENCE MONTHLY. 



ing the counties into three groups those in 

 which there were, respectively, jfo of an acre, 

 14 acres, and 4 - 8 acres to each person, the 

 corresponding rates of mortality from diph- 

 theria and croup were 12% 10"2, and 8 - 8 an- 

 nually for every 10,000 persons. The rela- 

 tion of certain railway lines to the diphtheria 

 death-rate is worthy of note. It was com- 

 paratively high in the greater number of 

 cities and towns traversed by the Boston and 

 Albany Railroad a leading road for traffic, 

 carrying large numbers of passengers, and 

 having many stations ; was less upon the line 

 of the Fitchburg road, which is of about the 

 same length but does less business ; and still 

 less upon the line of the more recently built 

 Massachusetts Central road. The term diph- 

 theria first appeared in the registration re- 

 ports of the State in 1858. The number of 

 deaths assigned to it increased rapidly till 

 1863, when 1,420 were registered. There 

 was then a rapid decline to 251 in 1867, after 

 which the annual number continued nearly 

 uniform (about 275) for seven years, when it 

 rose again to 2,610 in 1876 and 2,734 in 1877. 

 The census of 1890 gave the number of deaths 

 as 32,716. The diphtheria death-rate bore 

 no relation to the general death-rate, except 

 during the period from 1862 to 1867. In 

 1872, when the general mortality-rate was at 

 its highest point and infectious diseases were 

 generally very prevalent, the diphtheria death- 

 rate was far below the mean, and in 1876 and 

 1877, when the general death-rate was near 

 the mean, the diphtheria death-rate was at 

 its highest point. The author concludes, 

 further, that diphtheria is eminently conta- 

 gious ; that it is infectious by direct expos- 

 ure and through indirect media, but less so 

 than some other diseases, such as small-pox 

 and scarlet fever ; that overcrowding, faulty 

 ventilation, and filthy conditions favor its 

 spread ; that the direct influence of plumb- 

 ing and transmission through public and pri- 

 vate water-supplies is not proved ; that its 

 propagation is favored by soil moisture, damp 

 cellars, and general dampness of houses ; and 

 that the poison may remain dormant in 

 houses for a long period. 



Scientific Observation of Children. In 



a paper on this subject addressed primarily 

 to mothers, Mrs. Helen Adler has laid out a 

 plan of work of considerable scope, and 



calling for the exercise of careful judgment. 

 Mothers, the author says, " must first of all 

 learn to appreciate the value of true scientific 

 observation, must train themselves to observe 

 correctly, methodically. They must humbly 

 learn that their own powers of appreciation 

 are worthless without the strict selection of 

 valuable facts, the subordination of what is 

 interesting and delightful to them to the 

 universally interesting and profitable. . . . 

 Method, strict, logical method, is the first 

 desideratum ; then vigilant observation, ve- 

 racity, discrimination, and ingenuity in the 

 study of the child. Baby ways are charm- 

 ing and irresistible ; they will be no less so 

 when an attempt is made to discover the 

 order of progress that dwells in them." The 

 development of language alone is mentioned 

 as offering a fascinating field of observation ; 

 the study of the baby will and its evolution 

 another ; and the psychic life of the child 

 will seem somewhat nearer to us, the growth 

 of its faculties a little more clearly revealed, 

 if we trace the record of their development 

 day by day. Later in life comes the devel- 

 opment of the character of the child as a 

 social being. A practical direction is given 

 to these observations by appending to them 

 a classified schedule of the points to which 

 attention may be directed. 



Olives and Olive Oil. The olive is culti- 

 vated on about seventy thousand acres in the 

 department of the Alps Maritimes, France, 

 and yields a revenue of more than two mill- 

 ion dollars a year. Two species of the tree 

 are described by our consul at Nice as grow- 

 ing in the south of France : the oleaster, or 

 wild olive, which has a kind of thorn and 

 very short leaves, and produces only a few 

 small berries, which appear to be proof 

 against insect enemies ; and the sativa, or cul- 

 tivated olive, which produces a large fruit, and 

 is known in several varieties. The olive tree 

 flowers every year ; but, while some growers 

 advocate an attempt to gain a yearly crop, 

 the majority are content to try to get a good 

 crop every two years. Olives to be preserved 

 green are plucked in September ; those des- 

 tined for oil, from November till the follow- 

 ing May ; but the best results to crop and 

 tree seem to follow harvesting near mid-win- 

 ter when the olive is black ; while oil made 

 from olives gathered as late as February and 



