Dec. 31, 1885] 



NA TURE 



199 



N.N.W. Sunset-glow intersected by five horizontal dark cloud- 

 streaks in the west. On the 2nd inst. , at 4. 20 p. m. , five cucaulo- 

 slrati were visible in the west, separated by parallel and horizon- 

 tal orange-coloured bands. Above these were numerous (pro- 

 bably twenty) delicate dark lines traversing — also horizontally — 

 the upper roseate after-glow. On the loth and nth inst., some- 

 what similar phenomena were visible here. On the 15th inst., 

 with a light southerly air, eleven cloud-bands were seen by me 

 at 4.30 p.m. In this case only, they were not parallel to the 

 sea-line, but followed the direction of the west-north-west hori- 

 zon. I have seen the same appearances once or twice since the 

 last date. The above phenomena are new to me, and I have 

 not met with any detailed account of them elsewhere. I have 

 therefore ventured to address you on the subj ect. Can these 

 cloud-streaks represent stratified air-dust in the upper regions of 

 our atmosphere? W. Ainslie Hollis 



Hove, Brighton, December 26 



Iridesctnt Clouds 



There was a very striking display of iridescent clouds this 

 afternoon. I noticed it first at about 3.40 p.m. The prismatic 

 colours were pretty strongly marked, and the intense pearly 

 brilliance of the delicate cirri was most striking. It is still visible 

 (4.40 p.m.), though, of course, its lustre is much diminished. 

 A gale is blowing from the west, and there has been an orange 

 after-glow. Similar phenomena were described in your columns 

 about this time last year. They were well seen in this part of 

 the country. Edward Greenhow 



Earsdon, Newcastle-on-Tyne, December 28 



Yesterday, clouds very similar to those seen a year ago 

 made their appearance, and there were a few of them again 

 this morning. I first noticed them at u. 30 a.m., and they were 

 extremely magnificent after sunset, showing three or four spectra 

 of colour, and they were especially striking about 4.10 p.m., 

 when they appeared very bright against the purple glow of the sky. 

 Their chief difference from the clouds last December was that 

 they were not bounded by straight lines, and that there was no 

 special amount of blue in the colouring, as was usually the case 

 a year ago. The chief colours were pink and green. 



Sunderland, December 29 T W. Backhouse 



Ventilation 



In reply to the query of J. F. Tennant, there can be no doubt 

 that the cause of the failure of the celling ventilators is a de- 

 ficiency of fresh-air supply to the room. An ordinary chimney 

 with a fire will, if unchecked, draw an amount of cold air into 

 the room which would make the temperature about the same as 

 that of the outside air, and without enormous volumes of warmed 

 air it is, I think, impossible to expect any service whatever from 

 the system of ventilation from ceiling-flues, as recommended by 

 the writer of the article referred to. Since writing my first letter I 

 have seen a regenerator lamp attached to one of these ceiling- 

 flues, and the down-draught was so strong and persistent as to 

 reverse the natural current of the lamp, rendering its use impos- 

 sible. The air-inlet to my own rooms consists of a channel in 

 the wall of every room opening into ten one-inch holes at the 

 fireplace, but this, of course, is utterly inadequate to supply one- 

 tenth of the air required by the flue, and the ventilator and the 

 ventilating-shaft supplement this supply by working the wrong 

 way. Thos. Fletcher 



Warrington 



A very common source of trouble with respect to ventilation 

 is the absence of any arrangement for the supply of air to fires. 

 So long as a fire draws on the general atmosphere of the room it 

 is supposed to warm for its supply of oxygen, there must be the 

 "draughts" so often complained of, and people are warm on 

 the side next the fire, and cold on the other. I should suppose 

 this is what happens in Mr. Fletcher's case, described in his 

 letter in Nature (pp. 153-4). If so, there is simply a sort of 

 "tug-of-war" between the longer chimney-flue and the shorter 

 ventilation flue, with the additional advantage on the side of the 

 former that the column of air ascending the chimnsy is neces- 



sarily much warmer than that which should ascend the ventila- 

 tion flue. If, howevei', Mr. Fletcher will have a couple of holes 

 bored in his floor, one on each side of the fireplace, so as to 

 supply air directly to the fire, the "pull" of the fire on the 

 air of the room will cease, the room will be warmer, and his 

 ventilation flue should work satisfactorily. I warm thoroughly 

 a room with considerably over 2000 square feet of floor area by 

 means of three small stoves. When first used the stoves were 

 inefficient, as there was a draught all round each towards it. A 

 common rain-water pipe "bend," inserted in the floor imme- 

 diately in front of the aperture of each stove for admitting the 

 air supply, stopped the draughts, and at least doubled the effi- 

 ciency of the stoves as warmers. With the help of Tobin tubes 

 there is now a gentle current of warmer air from each stove. 

 The heated and vitiated air escapes through ventilators fixed in 

 the ridge of the roof. W. Wilkinson 



Eldon, Bishop Auckland, December 23 



Friction and Molecular Structure 



In your number of December 17 (p. 154) is a letter signed by 

 Mr. E. Geoghegan, referring to the effect of moderate friction on 

 the molecular structure of glass lamp-chimneys. This I have 

 very frequently observed, and it would be very interesting to 

 have suggestions as to its cause and means of prevention. I 

 often read under one of Sugg's Argand gas-burners, the chim- 

 ney of which almost invariably breaks on fii-st heating after 

 cleaning. First of all, washing was tried, to remove the mottled 

 milky stain which forms on the glass, and then rubbing with a 

 silk cloth or cotton rubber, but there does not seem to be much 

 difference in the result, as the glasses, the best I can obtain, 

 generally break. C. K. BUSHE 



Bramhope, Old Charlton, Kent, December 25 



The Longevity of Insects 



With reference to the longevity of insects, it is worth while 

 to record that we kept a ladybird from the September of one 

 year to the September of the following. She was a handsome 

 specimen of the seven-spotted ladybird, and her eggs, which 

 were laid in the winter, after passing through the miniature 

 crocodile stage, produced perfect insects in February. It is 

 curious to watch the imago emerging from its dusky case ; at 

 first no spots are visible on its buttercup-yellow "shards," which 

 contrast strongly with the jet-black legs and underneath ; but in 

 a very few hours the first brilliancy has gone, the spots appear 

 faintly, and in a few days the final red with the black spots is 

 established. E. 



December 28 



SOUTH AMERICAN BIRD-MUSIC 



MR. BURROUGHS, an American naturalist, in his 

 " Impressions of some British Song Birds," has 

 said : — " Many of the American songsters are shy wood- 

 birds, seldom seen or heard near the habitations of men, 

 while nearly all the British birds are semi-domesticated, 

 and sing in the garden and orchard. This fact, I had 

 said, in connection with their more soft and plaintive 

 voices, made our song-birds seem less to a foreign travel- 

 ler than his own." These words apply with much greater 

 force to the birds of South America, the species being 

 much more numerous and less well known than in the 

 northern portion of the continent ; while the true song- 

 sters are relatively fewer, owing to the presence of several 

 large songless families, such as the tyrants, humming- 

 birds, and others. 



The South American songsters certainly do not, like 

 those of Europe, mass themselves about the habitations 

 of men, to sing there as if sweet voices were given to 

 them solely for the delectation of human listeners ; they are 

 pre-eminently birds of the wild forest, the marsh, and the 

 savannah ; and the ornithologist or collector from Europe, 

 whose principal object is to inake a large collection, has 



