MISCELLANY. 



381 



limestone, thus forming a complete barrier 

 against attack. Inside the wall of masonry 

 are numerous mounds of earth, and within 

 the line of these mounds is a ditch 4 feet 

 deep and 20 feet wide. 



A Cheap Substitute for Bells. Mr. J. A. 



Judson, C. E., writes us from Dutch Island, 

 near Newport, that for several years past 

 he has used a steel bar in place of a bell, 

 with very satisfactory results. He caused a 

 bar of steel about one inch and a half in 

 diameter to be forged into an equilateral 

 triangle of about three feet on a side, with- 

 out uniting the two ends, thus forming an in- 

 strument similar in all respects except size 

 to the rude musical appliance called the " tri- 

 angle," used by negro minstrels and some- 

 times in brass bands. This is suspended from 

 one of its angles by a rope attached to a sim- 

 ple wooden frame, and is struck by hand with 

 an ordinary steel-faced blacksmith's ham- 

 mer. A cord attached to the triangle and 

 held in the left hand of the ringer prevents 

 its whirling about when struck. If neces- 

 sary, it may be permanently lashed, with- 

 out materially interfering with the vibra- 

 tions, and could then be rung by some 

 stationary mechanical device. " I may have 

 been fortunate," says Mr. Judson, " in find- 

 ing an especially suitable bar of steel for 

 the purpose, for it is certainly sonorous 

 and powerful, answering all the purposes 

 of an ordinary factory-bell, at merely the 

 cost of so many pounds of steel, and a 

 few hours of skilled labor." 



Heat as a Disinfectant. In the course 

 of some experiments, made with a view to 

 ascertain how far heat may be employed as 

 a means of disinfecting articles of cloth- 

 ing, Dr. Ransom, of Nottingham, found that 

 white wool, cotton, linen, silk and paper, 

 may be heated to 250 Fahr. for three hours 

 without apparent injury, although the wool 

 shows a faint change of color, especially 

 when new. The same may be said of dyed 

 wools and printed cottons, and most dyed 

 silks ; but one kind of dyed silk easily 

 turns brown by this heat, and pink silks 

 of some kinds are also faded by it. The 

 same temperature will, if continued for a 

 longer period, slightly change the color of 

 white wool, cotton, silk, paper, and un- 



bleached linen, but will not otherwise injure 

 them. A heat of 295, continued about 

 three hours, more decidedly singes white 

 wool, and less so unbleached and white 

 cotton and white silk, white paper, and 

 linen both unbleached and white, but does 

 not materially injure their appearance. The 

 same heat, continued for about five hours, 

 singes and injures the appearance of white 

 wool and cotton, unbleached linen, white 

 silk and paper, some colored fabrics of 

 wool, or mixed wool and cotton, or mixed 

 wool and silk. It is noteworthy that the 

 singeing of any fabric depends not alone on 

 the heat used, but also on the time during 

 which it is exposed. In the experiment, the 

 heat was obtained by burning gas with 

 smokeless flame, and conducting the prod- 

 ucts of combustion, mixed with the heated 

 air, by means of a short horizontal flue, 

 into a cubical chamber through an aperture 

 in its floor, and out of it by a smaller aper- 

 ture in its roof. Fixed thermometers showed 

 the temperature of the entering and outgo- 

 ing currents, which represented the maxi- 

 mum and minimum temperatures of the 

 chamber. A self-acting mercurial regula- 

 tor maintained the temperature of the en- 

 tering current at any required degree. 



The Science of Education. One of the 



most important papers read in the Section 

 of Economic Science of the British Asso- 

 ciation was that by Mrs. Grey on the " Sci- 

 ence of Education." The author complained 

 that in Britain there is no adequate or gen- 

 eral conception of what education is, and 

 therefore of the magnitude and complexity 

 of the facts on which a science of educa- 

 tion, which can never be an exact, but only 

 a mixed and applied science, must be based. 

 We start with a confusion of terms, using 

 education as synonymous with instruction ; 

 and the confusion of thought indicated by 

 this misnomer runs through our whole treat- 

 ment of the subject, theoretical and prac- 

 tical, and is shown in every discussion of 

 ,the subject. It is surely time that this 

 confusion should be replaced by a scien- 

 tific conception of the process which should 

 result in the most valuable of all products 

 human beings developed to the full extent 

 of their natural capacity. What is wanted 

 is, that teachers, like practical navigators, 



