Ai'KiL 7, 18S2.] 



KNOWLEDGE 



i95 



failures — the causes are so various, that tliey require in each 

 case to lie traced to their source, and not iiifreijuently the 

 cause will not l>e discovered. The amateur, therefore, 

 must not be discouraged Viy failures. 



Advice will naturally be sought as to the outfit required ; 

 and the reply to this is that if expense he no object, the 

 best apparatus procurable should be purchased at the out- 

 sot. Our advice is, determine what you wish to do, and 

 then go to a dealer in photographic materials and appa- 

 ratus, and he will supply a list of M'liat is necessary. If 

 pictures not larger than y x -t will satisfy the ambition of 

 the beginner, the expense of the outfit will not be great — 

 £■") will supply camera, lens, and chemicals sufficient to start 

 him in his new and, as he will soon find, fascinating hobby. 

 Perhaps the most useful size for the camera for the tyro is 

 ine for taking pictures 7 x •">, and if a lens of the "rapid 

 rectilinear" form be adopted, poitraits as well as landscapes 

 may be taken with it, and it will not Vie necessary to have 

 a special portrait lens for that class of work, for the 

 amateur will soon find that portraiture is not the least 

 pleasing of the uses to which he may put his apparatus. 



Tt is assumed that all the necessary apparatus and 

 • hemicals have been obtained, and we must now describe 

 how they are to be used ; and it is assumed, also, that the 

 luiateur will commence with the wet collodion process. 

 I laving become expert with this, he will have comparati\"ely 

 little difficulty in practising the newer and quicker process 

 with gelatine dry plates, which will be described later. 

 First of all, it is necessary that the glass used sliould be 

 if good quality and perfectly clean. Patent plate-glass 

 is, of course, to be preferred : but any glass of good 

 |uality will answer. The glass must be perfectly 

 '■lean ; and, to efl'ect this, whiting or Tripoli powder 

 may be made into a thin paste with alcohol and water — 

 ^ay equal parts. After the glass has been washed in 

 I lean water, a small quantity of the Tripoli paste may 

 I'l' dropped on to the glass, tlien rubbed over hotk sides of 

 the glass, and then rinsed otl' under a tap of running water. 

 The cloths nsed for drying the plate should not be used for 

 uiy other purpose, and should bo washed without soap. 

 \\ hen dry, the plates should be polished with a clean 

 '••ather, kept strictly for the purpose. If breathed on, it 

 ■'. ill be seen at once whether the glass is perfectly clean, 

 iii-fore coating the plate with collodion, all dust should be 

 ' Tushed of!" with a large, soft Virush, kept for the purpose. 



BRAIX TROUBLES. 



Ii;uiT.vi!ii,ri'v. 



VMOXG the most characteristic signs of mental weari- 

 ness, irritability may be mentioned. We use the 

 \\ord rather in its technical than in its ordinary sense. 

 Nervous irritation may be indicated iiuite as much by 

 ■-;loom and melancholy, as by temper or impatience. When 

 we find ourselves disposed to take unreasonably gloomy or 

 unreasonably fretful views of our afl'airs, to be troubled or 

 vexed (that is, made sorry or angry) by trifling matters, we 

 may be assured that there is something wrong with us. The 

 mischief may be Viodily, or it may arise from external 

 causes ; but usually — at any rate with those who exercise 

 the mind more actively than the body — the cause of the 

 change is mental. It is not always easy to distinguish 

 between these various forms of irritability. Those who are 

 artected by the east wind can ascertain, when they find them- 

 selves out of sorts, whether the wind is easterly or not; but 

 : probable that the mere .'iabilit be thus affected 



is a sign of nervous weakness, which may result from 

 mental overwork.* And there are some meteorological 

 causes of irritability not so easily inquired into as the 

 influence of an easterly wind. (Has it been commonly 

 noticed, or is the experience exceptional in the writer's 

 case, that when the mind has been heavily taxed, blusterous 

 weather produces the etlects usually attributed to easterly 

 winds ?) 



Again: some of the forms of irritability due to 

 bodily mischief are not easily distinguished from those 

 due to mental overwork. Thus, a case is related of 

 a young man noted for his gentleness, who, forming 

 one evening a member of a brilliant party (his com- 

 panions being of his own age), was (juarrelsome and 

 cross-grained, wrangling with, and in the end ofl'ending, 

 everybody in the room. Two hours after he was seized 

 with nephritic torments, caused by a calculus, which 

 did not cease to trouble him till the next day. The writer 

 can recall an even more striking case of the sort in his own 

 experience. He had Vjeen struck by his own exceeding ill- 

 temper (which, utterly wrong-headed though ii seemed, he 

 felt quite unable to control), while visiting, at the request 

 of several of the ]>rofessors of Yale College, the laboratories 

 and technological collections of that institution. He could 

 in no way distinguish his irritability from that which he 

 had learned to regard as the effect of over-work. But it 

 continued (though he had had and availed himself of an 

 opportunity for resting) for more than twenty-four hours. 

 Soon after (for there was an interval during which the 

 sense of ill-temper and despondency passed away), he was 

 attacked by renal tortures, which, unlike those of the 

 amiable young man of the previous story, lasted more than 

 a week, and amply justified (in the writer's opinion) all 

 the ill-temper he had displayed beforehand, — if at least 

 the disorder of the nervous system before the attack could 

 be measured by the intensity of the pains suffered during 

 the attack. 



Usually, however, an indefinable feeling of irritability 

 and ill-temper signifies that the mind has been overworked. 

 So, also, does that state in which, to use a commonplace 

 but convenient expression, everything seems to go wrong. 

 In reality, we do everything wrong, though we may be 

 unable to recognise any diti'erence between our way of 

 attending to those slight matters on which the pleasant 

 progress of our work depends and onr customary methods. 

 We misplace this and upset that, tear, smear, blot, and so 

 forth, not because the fates are for the time being against 

 us, but because we are weary and overwrought (though we 

 may not be conscious of it), and our hands and fingers 

 are not under the usual control of the mind and will. 



* Dr. Forbes Winslow describes a curious instance of morbid 

 irritability of this kind. "A military man, suffering from severe 

 mental dejection, was in the habit," he tells us, " of promenading 

 backward and forward in a certain track, towards evening, on the 

 rampart of the town iu which ho resided. When he walked for- 

 ward, his face fronted the east, where the sky was hung with black, 

 as was, alas ! his poor soul. Then his grief pressed doubly and 

 heavily upon liini ; he was hopeless and in deep despair. But when 

 he turned with his countenance towards the west, where the setting 

 sun left behind a golden stream of light, his happiness returned. 

 Thus he walked backward and forward, with and without hope, 

 alternating between joy and melancholy, ecstasy and grief, in 

 obedience to the baleful and benign influence[s] of the eastern anil 

 western sky ! " Altieri siys, in his " Memoirs," " I have observed, 

 by applying to my intellect an excellent barometer, that I had 

 greater or less genius or capacity for composition according to the 

 greater or less weight of the atmosphere : a total stupidity during 

 the solstitial and equinoctial winds ; an infinitely less perspicacity 

 in the evening than in the morning; and much more fancy, 

 enthusiasm, and invention in midsammer than in the intervening 

 months." 



