•80 



HARDWICKE'S SCIENCE -GOSSIP. 



But in some parts of the country, as late as 1756, 

 they appear to have been unknown. There is an 

 anecdote told of a lady of VVigtonshire bringing 

 some potatoes in her pocket to church to present 

 to a friend as a rarity, but the string of her pocket 

 breaking as she was in the act of going out, on the 

 dismissal of the congregation, she lost her burden 

 ■in the passage, the contents of which created con- 

 siderable speculation. We have uo records of the 

 «early practice and progress of potato husbandry in 

 Ireland ; but towards the end of the seventeenth 

 century, we are informed by Houghton, in his 

 " Collections on Husbandry and Trade," that during 

 the wars of that period, when all the corn was de- 

 stroyed by the plundering and pillaging of the 

 soldiery, the potato crop seemed, in a great mea- 

 sure, to supply the inhabitants with food, for he 

 observes, " unless the soldiers had dug up all the 

 ground where potatoes grew, and sifted it, they 

 could not have extirpated them." 



These facts and extracts serve to show how, by 

 what gradual and almost imperceptible steps, this 

 most valuable root has been brought to its present 

 state of perfection, for there can be indeed but 

 little doubt that the imperfect modes of cultivating 

 and cooking the potato were, in a great measure, 

 the cause which prevented its more speedy adoption 

 as a wholesome article of food. 



It is related by a person who was invited to taste 

 the first potatoes grown in Forfar, that the roots 

 had been merely heated, and that they adhered to 

 the teeth like glue, while the flavour was far from 

 agreeable. The food was about to be condemned, 

 when a gentleman, who had tasted the potato in 

 Lancashire, accidentally arrived, and caused the 

 rejected roots to be put back into the hot turf-ashes, 

 till they became as dainty as they had before been 

 ■aiauseous. 



{To be cont'umed.) 



"TURNTABLES" AND "MOUNTING." 



•Til HERE are few microscopists who, from being 

 -*- unable to prepare their own slides, have to put 

 up with purchasing such at the dealers', but meet 

 with the annoyance every now and then of the cells 

 or covers giving way ; and although they may go to 

 the unlucky vendor and complain, and perhaps have 

 them exchanged, yet it is touching an innocent 

 party on a tender point, while the real culprit may 

 have the good luck to escape scot free. It would 

 seem to be a very simple and easy matter to cement 

 two pieces of glass together with an intermediate 

 ring of some sort or other to hold them apart for 

 the reception of the object ; but in practice tiiere 

 are so many obstacles to contend against that it is 

 by no means so easy of accomplishment as might be 

 expected, and scarcely any of the uninitiated would 



be able to form any adequate conception of the 

 amount of anxious care and forethought that has 

 been expended upon such a seemingly trivial affair; 

 and yet, in spite of all ordinary care, failures will 

 sometimes occur, although it is probably owing as 

 much to defective means as to want of care. The 

 first great obstacle to be considered is the effect of 

 expansion and contraction, or the different degrees 

 of expansibility among the various substances em- 

 ployed ; for even if the cell itself be also of glass 

 the contents of the cell, whether air or fluid, expand 

 in a different ratio to the glass, and thus tend to 

 loosen the cell or the cover from its attachment, to 

 the detriment of the mounting. An apparently 

 obvious remedy against these results would be to 

 make use of a softer and more tenacious cement, 

 such as would admit of this contraction and expan- 

 sion without becoming detached ; but, unfortu- 

 nately, another evil then makes its appearance in 

 the shape of "air-bubbles" and "running in" of 

 the cement, so that a certain degree of consistence 

 as well as adhesiveness is essential to success. The 

 composition of these cements, however, must be left 

 for some future opportunity, as the immediate object 

 of the present communication is to call the atten- 

 tion of mounters, both amateurs and professionals, 

 to one other serious defect that is quite within their 

 power to remedy without putting tbemselves to any 

 great cost or inconvenience in so doing. 



Whatever may be the materials of which a cell is 

 composed, or may be put together with, it is indis- 

 pensable to its security that the outside shall be 

 well coated over with some protective composition 

 wdiether it be ornamental or plain, and in the case 

 of fluid mountings it is desirable to repeat this ex- 

 ternal varnishing at intervals, as a precautionary 

 measure of safety — hence, for this purpose a " turn- 

 table " becomes a necessity ; but as cells are very 

 rarely fixed in tbe middle of the slide, or any two of 

 them in the same relative place, the latter defect 

 involves an unnecessary amount of trouble and in- 

 convenience, besides a very serious loss of time, 

 through having to centre each slide separately, 

 which, by a little better arrangement of the turn- 

 table, may be easily avoided for the future. 



Glass slips are intended to be exactly one inch 

 wide and three inches long ; but as there is often a 

 variation of a tenth of an inch or more in both length 

 and width, it becomes evident that any mode to be 

 universal must admit of compensation in this re. 

 spect ; therefore the only possible plan is to make 

 two sides only of the parallelogram available to 

 measure from, and which is, fortunately, the easiest 

 plan to put in practice. The annexed sketch, half 

 tbe size of the original, represents the principal 

 wheel of a turntable I constructed about twenty 

 years ago, and which has been in use ever since 

 without having ever given rise to a feeling that any 

 further improvement could be made, seeing that it 



