HARDWICKE'S SCIENCE-GOSSIP. 



75 



to see the result, and this is it. From that day to 

 this, a good four months, the water in this jar has 

 remained as clear as crystal, and its living occupants 

 are apparently as healthy as the day they were taken 

 from their home on the shore. 



Jar No. 2, in consequence of my experiments in 

 feeding the actinia, did from time to time become 

 thick as regards the water, but by replacing this 

 from the reserve bottle and carefully straining the 

 other and keeping in the dark, I have so far suc- 

 ceeded that my two A. mesonht-yanthcmtmi have, by 

 producing young, become four, and no occupant has 

 died, but health and vigour is seen in all. 



Now I have, no doubt, been favoured so far with 

 suitable weather for such experiments, and it may be 

 a very different matter when the atmosphere stands 

 at a temperature of 60° or 70° instead of 40° or 50"^, 

 "but I intend then to stand each jar in a large saucer 

 of water, and to partially cover the jars with an 

 envelope of coarse canvas or flannel, which, by being 

 kept constantly wet by capillary attraction, will 

 produce coolness by evaporation, and thus preserve 

 a suitable temperature for the contents of the jars. 



Of course such an envelope will curtail the view of 

 the live stock, but the canvas coat may be made 

 removable. 



Much interest is afforded by a small tank of this 

 description, and the trouble connected with it is 

 almost 7iil. I shall be happy to give any one further 

 details as to starting a series of pint tanks if desired, 

 and I hope at some other time to report progress, 

 and to make some observations on the habits of the 

 inmates. 



Edward Lovett. 



Addiscombe, Croydon. 



MINERALOGICAL STUDIES IN THE 

 COUNTY OF DUBLIN. 



CONSIDERING the vast importance in modern 

 times of mineral products in connection with 

 manufactures or domestic requirements, it is surprising 

 that the science of mineralogy is not more generally 

 cultivated by those having a taste for natural science. 

 There are few districts in any country so barren as 

 not to afford some points of interest for the student 

 who diligently seeks them. Germany, ever in the 

 van of scientific knowledge, has done much to make 

 this study accessible and attractive to the masses, as 

 may be seen from the works of Groth, Naumann, 

 Plattner, and others. America, whose great mineral 

 resources offer an ample field for the development of 

 information, is also doing good work, nor is France 

 lagging behind in the matter ; but in the United 

 Kingdom few appear to think the mineral world 

 worthy of attention, as the paucity of scientific works 

 on the subject would seem to indicate, and for one 

 student who devotes himself to minerals, there are a 



dozen who pursue botany, zoology, or other kindred 

 subjects to the exclusion of everything else. 



And yet there are few branches of natural science 

 more fascinating to the lover of nature ; but its 

 difficulties are often magnified by those who have not 

 taken the trouble to dip more than superficially into 

 it. No doubt, for the proper study of mineralogy, it 

 it is necessary to use the knowledge of the mathema- 

 tician, the physicist, and the chemist ; but, given the 

 inclination, there is no reason why the earnest 

 student should find this more difficult to acquire than 

 any other branch of learning. By the aid of a good 

 elementary work, a piece of road metal, picked up by 

 the wayside, may give a valuable insight into crystal- 

 lography ; and for the expenditure of a few shillings, 

 a simple set of apparatus for blowpipe analysis may 

 be placed on his study table, which will afford him a 

 never-failing source of interest, and may possibly 

 lead to even more substantial results in after life. 



Having said thus much by way of preface, I now 

 propose to give a few notes of a couple of excursions 

 recently made in the neighbourhood of Dublin in 

 search of objects for analysis. In the first of these 

 excursions in August last, I had the advantage of 

 being accompanied by Professor J. P. O'Reilly, C.E., 

 of the Royal College of Science here, whose long 

 experience, both at home and on the Continent, has 

 qualified him to be regarded as a leading authority 

 on mineralogy. The vicinity of Dublin is not re- 

 markable for minerals of a workable kind, but there 

 is still much of interest to be found, and, at Professor 

 O'Reilly's suggestion, we selected the hill of Feltrim, 

 a locality within easy reach of Dublin, where a rather 

 remarkable quarry exists. A run of half an hour by 

 the Great Northern Railway brought us to Malahide, 

 a watering-place possessing many advantages of 

 situation and salubrity. Feltrim is situated a short 

 distance off, and consists of a singular-looking ridge 

 running nearly east to west, and rising almost 

 abruptly from the surrounding country. It is sur- 

 mounted by a ruined windmill, the whole forming a 

 most desirable locality for artistic students, from a 

 combination of rich colour, and the splendid view of 

 Dublin Bay to be had from the summit. The 

 district is in the lower part of the carboniferous 

 limestone formation which extends so generally 

 throughout Ireland, and is highly fossiliferous, con- 

 taining examples of Fenestella antiqita, Produdus 

 aculeatiis, P. mesolobus, P. semireticulatus, Spin/era 

 Uneata, S. striata, Eiiomphalus pcntaugidatiis, and 

 many other species too numerous to mention. Large 

 masses of the limestone here are dolomitised to a 

 considerable extent. The undolomitised portion, 

 that is to say, the masses lying between the dolomitic 

 ribs, as they may be called, furnish an excellent lime, 

 and in a large heap of material rejected by the 

 quarrymen, we found many objects of interest. 

 Crystals of calcite were abundant, many good-sized 

 sections affording excellent examples of the character- 



£ 2 



