Sept. 22, 1881] 



NATURE 



489 



economy is obligatory in girls' schools if any specific subject is 

 taken at all ; so that the chance of any of the others being intro- 

 duced is very much diminished. It must also be remembered 

 that these subjects are only allowed to be taught to children in 

 the Fourth hitandard and upwards ; while only about one-tifth of 

 the children in the boys' and girls' si;hools are to be found at 

 present in these standards. Aci.ording to the Report of the 

 Committee of Council for Education recently issued, there were 

 476,761 children presented for examination in these standards, 

 of « horn the following numbers only were examined in the science 

 subjects : — 



Mechanics ... ... ... ... ... 2,109 



Animal physiology ... ... ... ... 24,725 



Physical geography ... ... ... ... 34,288 



Botany 1.853 



Domestic economy ... ... ... ... 50,797 



Out of 489 boys' and girls' departments under the London 

 School Loard, the specific science subjects were taken up, as 



follows, during the year 18S0 : 



Mechanics in... ... ... ... 4 departments 



Atiimal physiology in ... ... 123 ,, 



Physical geography in ... ... 112 ,, 



Botany in ... ... ... ... 9 ,, 



Domestic economy ... ... ... 172 ,, 



Mr. Hance of the Liverpool School Board has favoured us with 

 an account of the .systematic scientific instruction which is given 

 in the Board schools if that town by a special science staff. 

 The subject selected for the boys is mechai ics as defined in the 

 New Code, with a considerable development in the direction of 

 elementary physics. It has been in ojieralion since 1877, and 

 the results for the year 1SS0-81 are given in the following 

 table : — 



Year Number Number Percentage 



1S80-81. presented. passed. of passes. 



Stage 1 797 ... 442 ... 55-46 



.. II 39S ... 261 ... 65-59 



III... 

 Total.. 



S2 



67-21 



[317 ... 7S5 59-6 



Domestic economy is also taught to the girls in a similar manner. 

 In Birmingham 1200 scholars are receiving scientific instruction 

 in ihe schools of the Board, and it is stated that the te.achers 

 uniformly find that " it added interest to the work of the school, 

 that the children Avere eager to be present, and that the les.sons 

 were enj 'ved, and were in fact giving new life to the schools." 

 The Board have found the results so satisfactory that they are 

 now furnishing their newest school with a laboratory and lecture 

 room. 



IV. As to science-teaching which does not fall under the pro- 

 visions of the New Code it is not probable that any large amount 

 is attemjHed. In Mancbester, however, the Board gives instruc- 

 tion to 404 children, all of whom have passed .Standard VI., the 

 highest ordinary standard, in the following subjects : phy^iology ; 

 acoustics light, and heat ; n agnetism and electricity ; che- 

 mistry ; practical chemistry ; botany. This teaching is illustrated 

 by means of good apparatus, &c., and has had a very beneficial 

 eflTect upon the science and art classes of the town. When it is 

 considered that the provisions of the Code naturally form, in 

 almost all cases, the extreme limit of what will be attempted in 

 the schools, it is important that they should be placed as high as 

 possible. This will be a great advantage to the stronger school^, 

 and no disadvantage to the weaker ones, as the higher branches 

 of science teaching will of course be optional. Your committee 

 have, therefore, arrived at the following conclusions: — 



I. As to objat Ic.'sons. That it is very desirable that Her 

 Majesty's Inspectors should take object lessons into account in 

 e-timating the teaching given in an infant school ; and that they 

 should examine the classes in the graded schools wherever object 

 lessons are given. 



II. As lo class subjects. That the teaching of such subjects as 

 natural hi-tory, physical geography, natural philosophy, &c., 

 should not necessarily be "through reading lessons," as oral 

 lessons, "illustrated by maps, diagram'^, specimens, &c.," are 

 undoubtedly better when given by a teacher duly qualified to 

 handle these subject*. They are of opinion, also, that it will be 

 desirable to allow a larger number of class subjects to be taken 

 up in any particular school, and to give in such ca e a propor- 

 tionately increased grant. 



III. As to specific science stib'ccts. That a knowledge of the 



facts of nature is an essential pait of the education of every 

 child, and that it should be given continuously during the w hole 

 of school life from the baby class to the highest standard. Of 

 course in early years this teaching will be very rudimentary ; but 

 by developing the child's powers of perception and comparison 

 it w ill prepare it for a gradual extension of such knowledge. 

 They consider also that the early teaching must be very general, 

 while the later may be more specific ; they think, however, that 

 the science subjects as given in Schedule IV. are fairly open to 

 objection, as being somewhat too ambitious in their nomenclature 

 and in their scope, and that they ought not to Le attempted unless 

 the child has had a previous training in natural knowledge 

 before entering the fourth standard. Thus the specific scientific 

 subjects ought not t') be distinct, as they practically are at 

 present, from the 1 vevious teaching ; greater latitude of choice 

 might be allowed in them ; and while they should not afford 

 technical instruction they should prepare the way for any tech- 

 nical classes or schools into which the children may subsequently 

 enter. In regard to domestic economy they are of opinion that 

 most of the points embraced in the schedule would be useful to 

 boys as well as to girls. 



IV. As to examinations. That in the appointment of Her 

 Majest)''s Inspectors some knowledge of natural science should 

 be con-idered as absolutely requisite ; ihat in examining the 

 children ihey should direct iheir inquiries so as to elicit not so 

 much their know ledge of special facts as their intelligent acquaint- 

 ance with the world of nature around them ; and that this may 

 be much better done by oral examination than by paper w ork. 



SECTION A — Mathematical and Physical 

 On tiic Economy of Metal in Conductors of Electricity, by Sir 

 W. Thomson. — The most economical size of the copper con- 

 ductor for the electric transmission of energy, whether for the 

 electric light or for the performance of mechanical w ork, would 

 be fi.und by coniiwring the annual interest of the money value 

 of the copper with the money value of the energy lost in it 

 annually in the heat generated in it by the electric current. The 

 money value of a stated amount of energ)- had not yet begun to 

 appear in the City price list. If 10/. were taken as the par 

 v.alue of a horsepower night and day for a year, and allowing 

 for the actual value being greater or less (it might be very Oiuch 

 greater or very much less) according to circumstances, it was 

 easy to estimate the right quantity of metal to be jiut into ihe 

 conductor to convey a current of any stated strength, such as the 

 ordinary strength of current for the powerful arc light, or the 

 ten-fold strength current (of 240 webers) which he (Sir William 

 Thomson) had referred to in his address as jiractically suitable 

 for delivering 21,000 horse-power of Niagara at 300 miles from 

 the fall. He remarked that (contrary to a very prevalent impression 

 and belief) the gauge to be chosen for the conductor does net 

 depend on the length of it thr..ugh which the energ)- is to be 

 transmitted. It depends solely on the strengih of the current to 

 be used, supposing the cost of the metal and of a unit of energy 

 to be determined. Let A be the sectional area of the conduc- 

 tor ; s the specific resistance (according to bulk) erf tbe metal; 

 and c the strength of the current to be used. The energy con- 

 verted into heat and so lost, per second per centimetre, is sc'jA 

 ergs. Let/ be the proportion of the whole time drn-ing which, 

 in the course of a year, this current is kept flowing. There being 

 31J million seconds in a year, the loss of energy per annum is 

 3l-5Xlo<'//<r7^ ergs . . . (l) 



The cost of thi*, if E be the cost of an erg, is 



3i-5Xio'y^<-'-^£M . . . (2) 

 Let f'be ihe money value of the metal per cubic centimetre. 

 The cost of possessing if, per centimetre of length of the wire, 

 at < per cent, per annum, is 



F^/20 . . . . (3) 

 Hence the whole annual cost, by interest on the value of the 

 metal, and by loss of energy in it, is 



l^^+3i-SXioV.c'£, . . (4) 

 20 A 



The amount of A to make this a minimum (w hich is also that 

 which makes the two constituents of the loss eqnal) is as 

 follows : — 



A = V^3i"5 • lo"/^^'^/-) 



= f v'(63 . io'/.f£-/K) . . (5) 



