HARDWICKE'S SCIENCE- GOS SIP. 



27 



ralist," eaters fully into the subject, aud shows that 

 the curve described by the fish in its aerial course 

 is not a parabolic one, which it would be were the 

 primary impetus the sole force expended, and there 

 is certainly nothing either in its specific gravity, 

 length of pectoral fins, or muscular development, 

 from which we can prima facie deny the power, 

 albeit limited, of true flight to this harassed denizen 

 of the deep. However, further observation would 

 be welcome on this qiicestio vexata. 



The term "Portuguese man-of-war," although 

 generally referring to Physalia, is also, and com- 

 monly, in the Mediterranean applied to the more 

 highly-organized Argonaut, Paper Nautilus, or Paper 

 Sailor, as it is called ; and here I think the blue- 

 jacket gives the more sensible appellation, for whilst 

 the former animal is powerless against the wind 

 and the tides, the latter can hoist its sails, with out- 

 spread tentacles " paddle its own canoe," aud like 

 some of our modern ironclads even settle into the 

 depths of the ocean upon slight provocation ! 



How many "devil-fishes " there are I have not 

 yet determined, — probably a good score ; the title to 

 the rank being earned apparently by anything big 

 and ugly. In England the sailor- applies the term 

 to the Lopkius piscatorivs, or Angler, also to the 

 Octopus and larger cuttles ; but probably his original 

 devil-fish is the Cephaloptera, or Horned Ray, an 

 animal which, from its grotesque appearance, enor- 

 mous power, and savageness when attacked, perhaps 

 best deserves the name. In the Gulf of Mexico 

 much sport is to be had in harpooning these fish, 

 the strength of some being so great as to enable 

 them to tow a man-of-war's gig with a crew of four 

 or five men at a very considerable speed. Their 

 vitality, too, is very great ; I have seen them almost 

 hacked to pieces before life became extinct, and on 

 one occasion was towed a considerable distance in 

 a large boat by one which had been thrice trans- 

 fixed with a cutlass, and afterwards lost by its 

 tearing itself from the harpoon. 



Another large cetacean belonging to the genus 

 Rata, met with in Jamaica and adjacent islands, also 

 receives the common name of " devil-fish." 



Although belonging to different genera and having 

 well-known distinguishing marks, shrimps and 

 prawns are almost convertible terms with seamen, 

 the former name being applied to the smaller 

 prawns, and the latter crustaceans when attaining 

 a large size, as in the East Indies, become dignified 

 by the name of Crayfish. 



But, as I have said, Jack has no regard for classi- 

 fication or the dogmas of the schools, nor does his 

 "master" much foster a study, the prosecution of 

 which in a practical form is perhaps more easy for 

 him than for any other class not endowed with 

 wealth and abundant leisure. It is but too true, as 

 a recent writer has remarked, that naval officers 

 have been far outstripped in their contributions to 



natural science by their brethren in the mercantile 

 service ; and we had hoped that when that magnifi- 

 cent pile at Greenwich was converted into an educa- 

 tional establishment for the Royal Navy, a niche 

 might have been found for the study of "Nature." 



Robert Nelson, R.N. 



THE MICROSCOPE AND MICROSCOPIC 

 WORK. 



No. II— By E. Kitton. 



TTAVING briefly described our workman's tools, 

 *--*- we will endeavour to give some idea of the 

 work he did with them. 



Our readers must not suppose that Leeuwenhoek 

 ever wrote a book on " microscopy." He used his 

 microscopes to enable him to see more of the struc- 

 ture of a plant or animal than the unassisted eye 

 would permit him to do ; and that is all a scientific 

 man does at this present time. Microscopes, in fact, 

 are nothing more than complicated spectacles, and 

 often not half so trustworthy. 



One of the subjects he treats upon is "the Oak." 

 The following is the heading to the chapter : — 

 " The Nature of its Production ; the different 

 Degrees of Goodness in Oak Timber, and the Causes 

 of that Difference ; the Author's Opinion as to the 

 proper Season for felling Timber." 



This chapter is illustrated by several copperplate 

 engravings of magnified sections (transverse and 

 longitudinal), all of them admirably executed. The 

 figure of a portion of a transverse section is 11 in. 

 in length and 4 in. in breadth, the actual size of the 

 fragment being £ of an iuch long and -^ broad, an 

 amplification of about 72 diameters. " This species 

 of timber tree has five different kinds of vessels, 

 three rising perpendicularly, and two extending or 

 spreading horizontally. The insides of these vessels 

 are full of a kind of vesicles or little bladders, com- 

 posed of very thin membranes or skins. The second 

 sort of these perpendicular vessels is much smaller, 

 and is also composed of exceeding fine membranes 

 intermixed with a kind of spots which, by the micro- 

 scope, appear to my eye like globules or little balls. 

 The third kind of these perpendicular vessels is 

 exceedingly small, but in great numbers ; likewise 

 composed of excessively minute membranes. All 

 the perpendicular vessels, which are found in so 

 small a piece as that before represented, and which 

 in size is about the ninetieth part cf a square 

 inch, do amount in number, in my opinion, to 

 twenty thousand. So that an oak tree of four feet 

 in circumference contains, according to my com- 

 putation, more than three thousand two hundred 

 millions of these perpendicular vessels. 



"These perpendicular vessels do for the most 

 part infuse or instil their juices into other vessels 

 which are almost innumerable, lying in a horizontal 



c 2 



