242 



NATURE 



\yuly 25, 1872 



Having made this assumption, the rule that the sum of the squares 

 of the remaining errors is a minimum follows very simply : vii.- 

 the late Memoir of Hansen, art. 3. 



With regard to the practical application of the Method of 

 Least Squares, I think the whole honour of its introduction 

 belongs to Gauss. The rules which he and his scholar Enckc 

 have given for the application of the method, and for executing 

 the numerical operations, are so complete and perfect that but 

 little more can be desired. 



Washington, July 4 As.A.rH H..\i.i. 



Solar Rainbov/ 



On the lOth instant at about half-past seven in the evening I 

 saw part of a well-defined rainbow about 5° west of the zenith, 

 the convexity of the bow towards the setting sun, which at the 

 lime was about 3° above the horizon. Light clouds were passing 

 beneath the bow. Tliere was no rain. 



Brighton, July 15 GicoRGE Dinnow 



Hive Bees t. Mechanism 



I HAVE never followed Huber through his wonderful researches 

 into the astounding working proceedings of hive bees — that elder 

 Huber, who, by the way, aided by so admirable a spouse, 

 brought his researches to so successful an issue, notwithstanding 

 his blindness. Hence my excuse, if what I attempt to describe 

 as being original to my own sense of observation, prove not so to 

 others. I think it is conceded universally that amongst other 

 leguminous plants peas have ever been secure from cross fertili- 

 sation, one variety with the other, in so far as natural influences, 

 insect agency, &c., are concerned. Our stocks of garden peas, 

 though known to run weedy and grow inferior when cultivated 

 too long upon one kind of soil, very rarely, if ever, sport or vary 

 as other plants placed in juxtaposition of species, especially 

 varieties, are known to do. So decidedly has this fact been con- 

 firmed, that invariably sweet peas, even when it is desirable to 

 grow them true to name, arc sown in ro^^•3, side by side, whites, 

 scarlets, blues, &c., with the utmost impunity. And this is 

 wholly owing to tlie fact that the floral envelopes are 

 so securely wrapped around the pistil and the stamens, 

 that these parts cannot be reached without the exertion 

 of more power than the strength bees and similar 

 winged insects are supposed ordinarily to possess ; unless, indeed, 

 mechanism be called to their aid — a science in itself, but which, 

 nevertheless, has been resorted to in the instance to which I 

 would direct attention. Here then the hive-bees methodically 

 bare the stamens by sheer mechanical force, .and rob each of its 

 load of pollen by sense of touch alone. And this they do in tliis 

 wise. Alighting on the fl/<r or "wings" of each bloom, they 

 first of all press their heads up under the base of that \ivci of the 

 papilionaceous corolla called the "standard," or -•iwilliim, and ex- 

 tract what nectar they find. Then, with their little heads firmly 

 pressed therein, and holding fast by the four fore legs, they 

 exert their power, thus artificially contrived, by treading down 

 both the aforesaid wings and the "keel," or carina, which so 

 securely envelopes the sexual organs, that they protrude, so that 

 the anthers are laid bare, when they generally rub the pollen off 

 the stamens on to their hairy bellies, only occasionally using one 

 hinder leg to aid them. It will be seen that they do this with 

 their hinder legs and body, at a time when their heads are entirely 

 hidden from view. I have tested these parts in regard to tlie 

 pressure needed to disclose the pollen thus, and find that a pres- 

 sure of half 10 three quarter ounce is necessary ; and computing 

 the weight of an individual bee to lie about the sixteenth of an 

 ounce, we see what an amount of power must be exerted in tliis 

 hind-before, or blindfold manner, by these interesting little 

 creatures. 



I should add, however, though I have been a selector of sweet 

 peas for more than a dozen years in other parts of the country, 

 as the selection sold liy some seedsmen with my signature 

 attached confirms, I nevertheless have not previously believed 

 in any power possessed by insect agency to thus destroy selec- 

 tions. Here, at Valentines, however, being only seven miles 

 from London, it would appear that the bees, like town sparrows, 

 are unusually "wise in their generation," and that, owing to 

 scarcity of honey-yielding materials, they are driven to such 

 wonderful feats as I have explained. 



WlI,T,l.\M E.\RLEV 



The Gardens, Valentines 



The Red Rocks 



If the peroxide of iron was deposited (.is in the Swedish 

 lakes) as brovn hydrous peroxide, and if long boiling in the 

 laboratory may be considered analogous to evaporation in an in- 

 land sea, then it would a|>pear from the following extract from 

 Watts's "Dictionary of Chemistry" that there is no difficulty in ac- 

 counting for the colour of the red rocks : — 



"A remarkable insoluble modification of ferric hydrate is 

 produced by boiling the ordinary yellow hydrate to 2 Fe, O3 3 H„o 

 (precipitated from the chloride by ammonia) in water for seven 

 or eight hours. The colour then changes from ochre-yellow to 

 brick-red, and the hydrate thus altered is scarcely acted upon by 

 strong boiling nitric acid, and but very slowly by hydrochloric 

 acid. In acetic acid, or dilute nitric or hydrochloric acid it 

 dissolves, forming a red liquil, which is clear by transmitted, but 

 turbid by reflected light ; is precipitated by the smallest quantity 

 of an alkali salt or a sulphate ; and on addition of strong nitric 

 or hydrochloric acid, yields a red granular precipitate, which re- 

 dissolves on diluting the liquid with water." 



The change of colour from brown to red is readily obtained by 

 boiling the hydrate in a flask for several hours, a; described above. 

 The change is gradual, and before becoming finally red the pre- 

 cipitate is of a chocolate colour, corre.sponding'with that some- 

 times observed in the red sandstones. 



Small pieces of white sandstone, introduced into the flask 

 during the boiling, are of course coloured red, and resemble red 

 sandstone when taken out and dried. R. D. P, 



Instantaneousness of Lightning 



DuRlNr, a recent night thunderstorm I got out my colour-top, 

 with the usual disc of so-called primary colours arranged to blend 

 into grey or white on rotation, in order to show to my children 

 the instantaneousness of the lightning, and that by its light 

 the disc would, as I had no doubt, appear stationary in one or 

 several successive positions according to the character of the 

 flash, as it does by the light of an ordinary electric spark from a 

 Leyden jar or induction coil. On trying the experiment, how- 

 ever, by turning the disc (about forty times in a second) at a 

 window in a dark room opposite to the cloud in and from which 

 the discharges were taking place, I found that this was only very 

 partially the case. When the direct stroke was actually visible, or 

 only slightly veiled by cloud, the effect I looked for was pro- 

 duced, the bands of colour standing out clear and apparently 

 motionless ; but at other times during the apparently (to the eye) 

 prolonged ilash, the colours blended so as to indicate a con- 

 tinuous fainter light in addition to the occasional instant.aneous 

 appearance of definite colour and form due to the intermittent light 

 of the discharge. Of course I s.atished myself that there was no 

 other light to account for this, the night and the room being very 

 dark in the intervals of the flashes, and I repeated the experi- 

 ment in another night storm (on the nth) with just the same 

 result. The effect appears to be due to the retention of light in 

 the cloud by phosphorescence, and, so far as I can find on in- 

 quiry, does not seem to have been noticed before. 



If my view is correct, it would explain the fact that distant 

 lightning at night, when no cloud is in sight, is apparently so 

 much sharper than when nearer. 



. / pivpos to the subject, a letter to the Times describing the 

 storm of the nth inst., speaks of the lightning "flickering 

 with a perceptible rustle " — a curious instance of transference of 

 impression from one sense to another, the visu.al sensation of 

 flickering being exactly analogous to the auditory sensation of 

 rustling. B. W. Smith 



Hanipstead, July 20 



Severe Thunderstorm 



A HEAVY thunderstorm jiasscd over this neighbourhood this 

 afternoon. One of the flashes was followed by a smart " snap " 

 like that of the discharge of a large Leyden jar, or the explosion 

 of a heavy percussion cap. The interval between this noise and 

 the crash of the thunder was about half or three-quarters of a 

 second. I have not unfrequently noticed a hissing noise imme- 

 diately preceding a violent clap of thunder, but never anything 

 so distinctly resembling the sound of the ordinary electric spark. 



Alex. Be.\zeley 



Willesden Lane, Kilbum, July 23 



