588 



• KNOWLEDGE ♦ 



[May 12, 1882. 



lArbirlus. 



"ABIDE ACROSS TIIK CHANNEL"* 



VL'riiOUClH t'oloui'l Uurnaby's buUooii rick- was not 

 iiitoiuleil for sdontific oljsor\ atiou, this book lias 

 iiitiTcst for the student of science, bcsitles being a gijiphic 

 account of a balloon ride. The greatest litight attained by 

 Colonel IJuinaby in this ride was about two rnilcs, and at 

 that elevation the teniperature was four degrees below the 

 freezing-point, while at an elevation of TiOO feet, a few 

 minutes before, the temperature had been 48" in the shade. 

 The account of the balloon's descent suggests, as usual, that 

 li;illoonists might with advantage devote some of that in- 

 genuity to devise safe ways of Ijringing a balloon to rest on 

 tlie ground, which has hitherto been fruitlessly expended 

 on attempts to guide the balloon through the air. As a 

 .scientific statement, Col. Burnaby's assurance respecting 

 till- etiect of the balloon's apparition on hens is open to 

 nuestion. " Thank Heaven I have seen it," cried a middle- 

 .•iged female. " It passed over my Louse like the, dome of 

 a cathedral ; and all my hens are still in con%iilsions of 

 tVight at its appearance." On which the advocate of 

 Cockle's Antibilious Pills gravely a.ssured her that " the 

 apprehensions of her hens would not diminish, but rather 

 increase, their laying powers." He should have added that 

 all eggs thereafter laid by those hens, would be marked 

 with a balloon in full career " like the dome of a cathedral." 



FLOWERS IN MAY. 



AT the opening of May, by far the commonest buttercup in our 

 meadows is tlie bulbous species (Ranunculus bulbosus.) It 

 ^TOws almost everywhere. Buttercups as a group may be always 

 easily rccof^uised by pulling out the petals, when they irill be seen 

 to have a small hollow scale near the base. The bulbous kind is 

 kno^vn both by the way its calyx is turned back tightly against the 

 .stalk, and by the rough bulb formed bj' the lower part of the stem. 

 \a the month wears on, the tall meadow buttercup (li. acris) 

 becomes commoner in the fields : its calyx grows in the normal 

 fashion, enclosing the petals, and the middle division of its leaves 

 starts from the same point as the outer ones. A third species found 

 almost as universally is the creeping buttercup (U. repens), exactly 

 Hko the last in most respects, but with rooting runners and the 

 central leaflet on a separate stalk, apart from the two-side leaflets. 

 Tlie water crowfoot {R.arivaiili.-) has white flowers and finely-divided 

 submerged leaves with larger floating ones : it is common in sha'l nv, 

 muddy water. The ivy-leaved crowfoot (R. Jiederaceus) differs 

 from it only in the absence of the submerged leaves ; it creeps on 

 mud beside the water. 0! tl-.e rose family, two or three little 

 potentillas may be found abundantly. They Iiave yellow flowers, 

 and may be roughly recognised by their double calyx. The tormentil 

 (/'. tormenUlla) has only four petals; it grows on high, windy 

 ■places. The cinquefoil (P. reptans) has five petals and five divisions 

 10 its strawberry-like leaf. Silver-weed (P. anserina) has similar 

 flowers, but many little leaflets arranged in two rows on each side 

 of a long stalk. Both those are road-side weeds. Herb-bennct 

 ff.Viim vrhanvm) much resembles the iiutentillas in flower and in 

 its donbic calyx, but is a taller and weedier iilant, with little hooked 

 fniitsforming a sort of rough burr. It is common in hedgerows. The 

 hedge itself blossoms now too ; its hawthorn bushes are also roses 

 by family; notice thou- single calyx. The pinks are another family 

 well represented this month. As a rule, most of the small white 

 flowers growing in ordinary situations, mtli a single capsule in the 

 centre of the flower, filled 'with seeds arranged ccmrally around an 

 .itis, are almost sure to be pinks. The smaller kinds have the 

 calyx in separate pieces. Of these, mouse-ear ehickweed ICerastium 

 ruUjaltim) has five split petals, and a capsule funnily cocked up at 

 the end and opening in ten teeth. It grows everywhere. Common 

 ehickweed (Stellaria media) has flowers much the same in appear- 



• " A Ride across the Channel, and other Adventures iu tlio Air." 

 By Col. Fred Burnaby. (London : Sampson Low, Marston A Co. 

 1HS2.) One Shilling. 



an 'c, but its capsile opens in five valves, and it may easily be recog- 

 nised by u single line (<f hairs running down one side of the stem. 

 Sandwort (Arennriii frinervit) looks very Hko the last, and can only 

 be (liscrimioated by its petals, which aro entire instead of being 

 two-cleft, and by the absence of the line of hairs. The larger pinks 

 have the calyx united into a sort of cup or tube. Two of them are 

 common this month— red campion (Ij\ichnis diurna), which is pink, 

 with scentless flower.* ; and white campion (L. xesperlina), which is 

 white and scented. Ragged Robin (L.floH-evcnU) ia very like the 

 first-named, but has much-divided petals, and a less swollen calvx. 

 The veronicas arc another group that can be well studied iu May. 

 They have blue flow er.", the petals united into a tube at the base, four 

 lobes to the corolla, and only two stamens. These peculiarities will 

 at once distinguish them from any other Knglish plants. Some of 

 them have the flowers arranged in leafless spikes starting from the 

 axils of the leaves. Two such may be found in May : I'. rham<e- 

 dri).'<, the germander, with hairy leaves and two lines of long hairs, 

 one on each side of the stalk; and I', hecrahvnria, brooklime, with 

 smooth loaves and hairless stem. The first haunts road-sides, the 

 second running streams. Another set of Veronicas has the flowers 

 solitary in the axils, not in spikes. One such, with little shining 

 leaves and tiny white blue-streaked blossoms, growing among 

 grass in fields, is the thyme-leaved speedwell (T. ierpijllifolia) ; 

 another, with ivy shaped leaves, is the V. hederwfolia ; a third, 

 with the upper leaves reduced to mere long, lance-like bracts, is 

 the wall veronica (1'. ari-ensif). Two others, very common in fields, 

 are Buxbaum's and the procumbent speedwell. They may be 

 known from the others by their broad, toothed leaves, not ivy- 

 shaped, and by their upper leaves like the lower ones, only smaller, 

 but they are harder to distinguish from one another. Buxbaum's 

 (r. Burbaumii) has a capsule twice as broad as long; the procum- 

 bent speedwell (!'. aijrestie:) has it about the same breadth as length. 

 We have only room for one other family, the orchids, known by their 

 spur and their tuberous roots, as well as by their curious twisted 

 ovary. The green-winged orchis (0. worio) may be recognised by its 

 green-veined sepals ; it is a southern plant only. The military 

 orchid (0. militaris), with a handsome spike of purple-red flowers, 

 iind a long, two-cleft centre lobe to the lip, belongs only to the 

 counties around London. The m«Ie orchis (0. 'iiascula), with a 

 pail- of spreading sepals, as if winged for Bight, is over early in the , 

 month. The spotted orchis {0. maculata) with lobed tubers and a 

 very dense spike, lasts through the whole of May. Altogether, 

 several hundred plants flower in May, and of these at least a 

 hundred and fifty are conimon everywhere, so that it is necessary' 

 to make a selection ; but whoever masters these five groups to 

 start with, wiU have done a good month's botanical work. 



Soi.AR Appakatus. — It will be remembered that M. Mouchot, a 

 short time ago, devised an ajjparatus for utilisation of solar heat, 

 and that M. Pifre made some important improvements on it. Very 

 different views have been taken as to the practical utility of such 

 an apparatus. Some help towards a right judgment now comes 

 from Montpellier, where a French Government Commission has 

 been experimenting with the apparatus for a year (1S81). Another 

 commission has experimented at Constantino, in Algeria, but the 

 results aro not yet published. The apparatus was of the known 

 form — a concave mirror, with blackened boiler in the axis, snr- 

 rounded by a glass envelope. The steam from the boiling water 

 «as condensed in a coiled tube cooled by water. The weight of 

 water di.stilled in an hour indicated the amoimt of heat uti- 

 lised; and observations with an actinometer from hour to hour 

 showed the amount of incident heat. The rates of these 

 two quantities was a measure of the economic efliciency of 

 the apparatus. The temperature and moisture of the air, &c., 

 were also carefully noted. The number of days of observation was 

 177, and of observations 030, and water was distilled to the amount 

 of 2,725 litres. Without entering much into numerical detail, we 

 may state that while the heat utilised in the most favourable cir- 

 cumstances per square metre per hour would be about equal to that 

 utilised from 210 grammes of coal (supposing about a half to be 

 utilised) — even the half of this is not attainable in our climate. 

 The sun does not shine continucusly enough for practical utilisation 

 of the apparatus. Iu very dry and hot climates, the possibility of 

 utilisation would depend on v.irious circumstances, such as the 

 degree of dilliculty of procuring fuel, the ju'lee and facility of 

 transport of solar apparatus, &c. We note in the report (by M. 

 Crova) that the efliciency of the apparatus is not proportional to 

 the heat intensity of the solar radiations, and hardly ever varies 

 in the same sense. The absolute quantity of heat utilised, on the 

 other hand, depends essentially on the temperature of the air; the 

 higher this is, and the less consequently the cooling, the greater 

 the amount of heat utilised. — T7ie Times. 



