96 



SCIENCE. 



[Vol. X. No. 237 



of the water at its surface had been 29° for some days, when a very 

 rapid and extensive fall in the temperature of the air took place ; the 

 following morning a film of ice half an inch thick had formed beneath 

 the surface, and had become fixed in position at the under surface 

 of the harbor-ice, whilst another film a quarter of an inch thick had 

 formed at the surface of the water, leaving a space between them 

 of about four and one-half feet. 



The dissipation of sea-water ice by the approach of spring takes 

 place at first much more rapidly from the upper than the under 

 surface, the atmosphere reaching the required temperature so much 

 sooner than the water. No sensible effect had been produced by 

 the water till its temperature exceeded 29°, when a loss of trans- 

 parency and vertical stratification of the ice became visible as the 

 first signs of its dissipation from beneath. In the mean time, of a 

 total thickness of four and one-half feet, eight inches of the upper 

 surface had been dissipated. W. A. ASHE. 



The Observatory, Quebec, July 29. 



but I have never been able to form a plan of hinderance that did 

 not soon prove impracticable. I have submitted with a sigh which 

 sometimes became almost a groan. My experience will, I fear, 

 have to be that of all who become interested in the subject. The 

 few words which I have brought together here may be of use in 

 checking the abominable fashion : otherwise they are useless. 



L. R. Peet. 



Yalaha, Fla., Aug. 11. 



The Florida Heron. 



Mr. Shufeldt'S article on the wanton destruction of our 

 heronries I found decidedly depressing reading. As an eye-witness, 

 he was able to give graphic pictures of both life and death. There 

 is perhaps no bird more beautiful, and at the same time more harm- 

 less to mankind. Indeed, it is its wonderful beauty that brings its 

 cruel death ; and the lack of fear and cunning, being never engaged 

 in mean work, makes it all too easy for the barbarous murderer to 

 approach. The heron is unfortunate. Nature has given it what 

 human vanity makes valuable ; and as only death can bring this 

 beauty within reach of the hard-hearted wretches, whom money 

 will induce to do many revolting things, the poor bird must die. If 

 this were the only instance of the kind, it would be yet more pain- 

 ful to our better natures, and those who are guilty of the outrage 

 would seem to us more blameworthy. In truth, it is the trivial use 

 to which the heron's plumes are put that makes the act of getting 

 them so detestable. The taste which calls for them is that of crea- 

 tures not yet developed to the highest form. Would a bird's feather 

 of any kind add to Venus de Medici ? Yet feathers, even those of 

 a buzzard's tail, would adorn an Indian female. When we con- 

 template any young lady of our age and generation, whose head is 

 so covered with feathers that the only part of the impression the 

 memory retains is that of the curiously combined mass of bird- 

 plunder, we are apt to be led to reflections which it would be cruel- 

 ty to the good-intentioned girl to make known to her. If the gentle 

 creature is really beautiful, that beauty cannot be adorned, except 

 from within. Any attempt to add to it externally by bright-colored 

 ribbons, flashing jewelry, or plumage, is always shocking to refined 

 minds. If beauty is lacking, the use of accessories to make up 

 what nature has denied is quite certain to excite contempt or com- 

 passion. 



The truly hideous practice, in vogue a few years ago, of wearing 

 the bodies of birds on the head, seems to have been too much, even 

 for the calloused sensibilities of people of fashion. To be attacked 

 by hungiy cats, or to see the famous myth of a spring chicken on 

 Biddy's proudly erect head, was too unpleasant. That there was 

 any sentiment about it is not easily conceivable. The silent woods 

 and meadows did not trouble the dissipated young female of the 

 city. She must be in the fashion, or she must die ; and, if she 

 reasoned at all, it was to the effect that it were better that birds 

 should die than that she should give up her slavish ghost. 



The fate of the heron is plain. After the slaughter has continued 

 until only here and there a shy one can be found, they will probably 

 assemble in convention, and migrate, to be seen by us no more. 



It would be idle to legislate, for only hunters know the way to 

 their resorts, and the former would hardly do for constables. The 

 very habits of a hunter would make it impossible to catch him at it ; 

 and, as he likes the sport too well, it would not be practicable to try 

 bribery. The horrible evil will have to be put up with until fashion 

 shall dictate something to take the place of the matchlessly beauti- 

 ful plumage, or until the frightfully persecuted bird takes itself to 

 remote regions impossible of access to man. 



This topic has occupied my mind at times for many years, and I 

 have mourned over the fate of the harmless denizens of our glades ; 



AnsTwers. 



12. Mosquitoes. — In Science for Aug. 5, 'T. J. H.' queries 

 concerning the re-appearance of mosquitoes on Staten Island seven 

 days after a storm. Though I have made some notes in reference 

 to Ciilex from time to time, this fact has never been observed. 

 Storms are always disastrous to insect-life, and will kill or blow 

 away moths and butterflies, as well as mosquitoes ; but that these 

 latter insects should re-appear in numbers seven days after a storm, 

 will depend entirely upon whether the majority of the pupas have 

 reached maturity or not at that time. Mosquitoes are present in 

 numbers all summer on the salt meadows, — indeed, I have scooped 

 with my two hands together hundreds of their larvae from the little 

 pools, — but it is only at intervals of about a month that they 

 swarm on the upland. During the latter week in May or first week 

 in June, and the first days of July and August, I have noted swarms 

 of mosquitoes in past years. The worst visitation of all is likely to 

 be the July one, or at least it has been generally so. On low ground 

 and near the meadows I have seen horses in July dressed in gar- 

 ments made for the occasion, and others decked with a profusion of 

 wild indigo, that shook violently as they trotted along. The older 

 residents remember well the mosquito visitation of July 3, 1862, 

 when the vegetables were left unpicked in the garden for a week, 

 and people wore mosquito-net over their hats. 



Wm. T. Davis. 



Tompkinsville, Staten Island, Aug. g. 



13. Electricity and the Earth. — In your issue of Aug. 5, 

 Mr. M. A. Veeder points out some passages in Deschanel's text-book 

 of physics, which he takes to imply that moist air is a good conductor 

 of electricity, and that the earth is a reservoir of electricity ; and 

 then he asks, " Has Deschanel been superseded ? " I do not happen 

 to have the book referred to at hand, but it does not matter. It is 

 true enough that one may complete an electric circuit through the 

 earth, or through any part of it, when there is proper conducting- 

 material at the wire terminals, not otherwise. The earth, in such 

 case, acts solely like a return wire to complete the electric circuit, 

 and its sole function is conductivity between points that differ in 

 electric potential. As most of the earth's surface is made of con- 

 ducting-materials, one may make connections for conduction almost 

 anywhere, and it is a great convenience to be able to do so ; but it 

 does not follow that the earth stores up any electricity at all, so that 

 it might be called a ' reservoir.' Electricity is but a transient 

 phenomenon, and, when it does work in no other way, is changed 

 at once into heat, in the earth as well as anywhere else. It is there- 

 fore improper and misleading to speak of the earth as a reservoir of 

 electricity. As to the effect of a damp atmosphere upon electrical 

 machines, it is well enough known that if means be provided for 

 preventing the deposition of moisture upon the surface of such 

 machines, by heating or otherwise, the machines niay be kept 

 electrified for an indefinite time. The electricity generated creeps 

 over the damp surfaces of wood or wax or varnish to the earth, 

 not through the air, whether moist or not. If moist air were a 

 good conductor of electricity, or if it were one of the best conduc- 

 tors, as was stated by Mr. Garriott, it is highly probable that tele- 

 graph companies would have found it out long ago, and ha\'e had 

 to insulate the wire from the air, instead of which they find it only 

 necessary to insulate from the posts upon which the wires are 

 hung. There is nothing new or strange about these things, except 

 it be, that, having been patent to all for so long a time, they should 

 be unknown to any who are pretentious enough to criticise the 

 labors of those who work according to knowledge, and at the same 

 time evolve out of their consciousness a theory unsupported by a 

 single experiment, and directly contradicted by all we do know. 



A. E. Dolbear. 



New York, Aug, 12. 



