344 



SCIENCE. 



[Vol. XIX. No. 489 



has not become broadly distributed, and has not occasioned 

 much trouble except in western Connecticut and in portions 

 of tlje Hudson River valley. 



The pear Psylla, Psylla pyri, also an importation from 

 Europe, has been with us at least from 1850, when, as re- 

 corded, it infested an old Virgalieu pear-tree in Greenbush, 

 N.Y. Since then it has become quite widely spread, and 

 seems to be rapidly increasing in number and in the injury 

 that it is doing. It was very destructive last year along the 

 Hudson Eiver in Columbia and Greene Counties. Mr. 

 Powell, an extensive f ruit^ower in Ghent, Columbia County, 

 has stated that it reduced his pear crop from an estimated 

 yield of twelve hundred barrels to an actual one of less than 

 one hundred barrels. Mr. A. F. Coe, of Coe Brothers, 

 owners of large orchards in Meriden, Conn., has written me 

 that on his retarn from Europe last September, he found 

 that two of his pear orchards had been devastated by the 

 Psylla. 



It is a small suctorial insect, somewhat resembling in size 

 and in its transparent steep-sloping wings the typical plant- 

 louse, but is readily distinguishable from that in its being a 

 jumping insect, whence it has been given the name of Psylla. 

 meaning in the Greek a flea. Its injuries are caused by the 

 large amount of sap which the myriads of individuals draw 

 from the twigs, buds, leaves, and leaf-stalks of an infested 

 tree, and the "honey-dew," which it freely deposits, thickly 

 coating tlie surface and thereby preventing the normal vital 

 action of the bark and leaves. 



Without consuming space vrith a detail of so much as is 

 known of its life-history, suffice it to say that at the present 

 time, or about the middle of June, the insect in its four 

 stages of egg, larva, pupa, and imago may be found upon 

 infested trees, and an abundant deposit of the honey-dew. 

 Later in the season the winged insects are more numerous, 

 and at the time of gathering the fruit, as the branches are 

 disturbed, they have been reported as "flying up in clouds 

 from the foliage." 



With the appliances now at our command it should not 

 be a difficult task to check and control the ravages of this 

 pest. Its most vulnerable period is doubtless, as in the 

 Aphididse, at the hatching from the egg. At this time proper 

 spraying with a kerosene emulsion will be fatal to it If 

 the spraying be deferred until the larvae have become half- 

 grown, the presence of the honey-dew would interfere with 

 the action of the kerosene. Early spraying should also kill 

 such of the eggs as may be reached by it, but many are placed 

 in positions where they are almost entirely protected. 



When the insect has passed to its winged stage, it has at- 

 tained comparative immunity in the alertness with which it 

 takes wing and leaves the tree upon the first motion com- 

 municated to the foliage by the impact of the spraying liquid. 

 But even so late as this the war against the insect should not 

 be abandoned, for multitudes may be destroyed, and the egg- 

 crop for the following year greatly reduced. The kerosene 

 emulsion will still be effective, but in its application all of 

 the ordinary spraying-nozzles should be discarded, even the 

 finest gauge of the Nixon nozzles, and a Vermorel used, ad- 

 justed to the delivery of the finest possible mist-like spray. 

 With proper care the emulsion may be distributed over the 

 entire foliage without scarce stirring a leaf and with the least 

 possible alarm to the winged tenants. Of those that take 

 wing — after circling about the tree for a while — on their 

 return to the leaves, their bodies will in most cases come in 

 contact with the liquid and cause their death. 



OfBoe ot the Stale EuiooQologi'.r, Albany, Jud" 13. 



THE TE?HN1CAL EDUCATION OF THE ELECTRICAL 

 ENGINEER.' 



BY DUGALD C. JACKSON. 



Perhaps it would be well to call my subject the " College 

 Education of the Electrical Engineer," for it is strictly of 

 the technical college course that I shall speak. We can 

 truly affirm that the technical education of an engineer does 

 not end until his work is ended, and the college course is 

 but the commencement of it. That the college course can 

 be made a very important fundamental part of this educa- 

 tion, is becoming more thoroughly appreciated as the work 

 of the technical schools comes into closer harmony with the 

 demands of the profession, and it is now generally agreed that 

 a technical college course, of the proper kind, forms a valu- 

 able aid towards the success of the average young man who 

 wishes to enter the engineering professions. It therefore 

 becomes a matter of no little moment to so arrange the 

 course that its usefulness will be a maximum. A few years 

 back, a college course entirely devoted to the training of 

 electrical engineers was unknown. At the present time 

 there is no dearth of such courses and their organization is. 

 progressing right and left, whence it is well to carefully con- 

 sider what requirements of the electrical engineer's profes- 

 sion they may be made to meet, in order that no powder be 

 wasted. It is neither possible nor desirable that the courses- 

 of study of electrical engineering students in the various- 

 schools should be alike, but a certain unity of purpose and 

 treatment should be observed, and all can profit by the sug- 

 gestions made by the practical man. 



With this in view, I present the subject to your attention- 

 as it is looked upon at the Engineering School of the Uni- 

 versity of Wisconsin. There is no originality claimed for 

 the ideas presented, as they are based upon the recorded ex- 

 perience of some of the country's most successful practical 

 men, and are virtually followed in such other engineering; 

 schools as make their courses thoroughly practical, and; 

 therefore, in the true sense, professional. I trust, however, 

 that a discussion will arise that is in proportion to the wide 

 importance of the subject to the electrical profession, and 

 that must result in a considerable increase in the efficiency 

 of the electrical engineering courses in our various colleges, 

 nearly all of which are still in process of crystallization. 



In order to enter the freshmen class of the best engineer- 

 ing schools, the applicant must have a thorough common- 

 school education, including mathematics through ordinary 

 algebra, a fair knowledge of English, a reading acquaintance 

 with German or French, a little elementary physics and 

 chemistry. This can be gained in the high schools of most 

 of the cities of this country. The high school timber (some 

 of it quite green) the college is required to work, and to- 

 work it to the best advantage requires no little careful de- 

 signing. In order that an engineer may use his abilities 

 and training most advantageously, he should have a good 

 general education, including a fair knowledge of literature, 

 history, economics and certain elements of law. This can- 

 not be expected to come from the high school, and you can 

 readily appreciate that an attempt to give a general educa- 

 tion in an engineering course can only result in sacriScing- 

 the good of the students by omitting essential fundamentals. 

 Thus, to have an average chance of proving successful, an 

 electrical engineer must be well grounded in three sciences- 

 besides those gained in the common schools, and which can- 



I A paper reai at the General .Meeting of the American Institute of Electri- 

 cal Englueer.-, t'Eu^ago, II)., Jiiue 6-6. 



