82 



NATURE 



{May 24, 1883 



The Soaring of Birds 



In the discussion about the soaring of birds which has lately 

 been carried on in Nature, I do not remember to have observed 

 that any one quoted from Mr. Darwin's account of the condor. 

 He says (" A Naturalist's Voyage Round the World," chap. ix. 

 p. 186) : — " When the condors are wheeling in a flock round and 

 round any spot their flight is beautiful. Except when rising from 

 the ground, I do not recollect ever having seen one of these birds 

 flap its wings. Near Lima, I watched several for nearly half an 

 hour, without once taking off my eyes: they moved in large 

 curves, sweeping in circles, descending and ascending without 

 giving a single flap. . . . The head and neck were moved fre- 

 quently, and apparently with force ; and the extended wings 

 seemed to form the fulcrum on which the movements of the neck, 

 body, and tail acted. If the bird wished to descend, the wings 

 were fjr a moment collapsed ; and when again expanded with 

 an altered inclination, the moaientum gained by the rapid descent 

 seemed to urge the bird upwards with the even and steady move- 

 ment of a paper kite. In the case of any bird soaring, its motion 

 must be sufficiently rapid, so that the action of the inclined surface 

 of its body on the atmosphere may counterbalance its gravity." 



Cambridge, Ma/ 17 JAMES CURRIE 



Intelligence in a Dog 



Some time since a friend of mine, Mr. J. W. Schaub, a 

 mechanical engineer at the Edgmore Ironworks of Wilming- 

 ton, Del., informed me of an exceedingly interesting case of 

 intelligence in a black and tan terrier belongi ig to him. The 

 old mother dog and her playful family entered his bedroom 

 while he was dressing, and one of the pups snatched his stock- 

 ing as he was in the act of putting it on, running out of the room 

 with it. The mother at once foil t wed the young offender, took 

 »he stocking from hi u, and returned it to the master. Mr. 

 Scbaub said that her conduct gave evidence of displeasure at 

 the action of the pup, and she impressed him with the idea that 

 she felt in sime way responsible for the conduct of her young. 

 Being greatly interested in the matter, Mr. Schaub contrived to 

 have the offence committed on many successive mornings, the 

 same performance being repeated each time. 



St. Louis, U.S., April 24 Francis E. Nipher 



Mid-height of Sea Waves 



Can any of your readers furnish me with the formula, or other 

 mean-, for finding the difference between the mid-height of a 

 sea-wave and the sea-level ? VV. Parfitt 



A CURIOUS SURVIVAL 



THE thirteenth Annual Report of the Deputy Master 

 of the Mint, just issued, contains some interesting 

 information showing how persistently an ancient system 

 of computing the value of bullion has survived in this 

 country. The facts are fully set forth in an appendix to 

 the Report by Prof. Chan Her Roberts, who has recently 

 and successfully advocated the adoption of the decimal 

 system in the bullion transactions of the Mint. In order 

 to make the matter clear, it may be well to state that the 

 Troy pound, still used in this country for weighing the 

 precious metals, is believed to have been derived from 

 the Roman weight of 5759'2 grains, the 125th part of the 

 large Alexandrian talent ; this weight, like the Troy 

 pound, having been divided by the Romans into 12 

 ounces. The earliest statute of I his kingdom in which 

 the Troy weight is named is the 2 Henry V. st. 2, c. 4, 

 but the Troy weight is universally allowed to have been 

 in general use from the time of King Edward I. The 

 most ancient system of weights in this kingdom was the 

 Moneyer's pound or the money pound of the Anglo- 

 Saxons, which was continued in use for some centuries 

 after the Conquest, being then known as the " Tower 

 pound," or sometimes the Goldsmith's pound. It con- 

 tained 12 ounces of 450 grains each, or 5400 grains, and 

 this weight of silver was a pound sterling. The Tower 

 pound was abolished in 1527 by a statute of Henry VIII., 

 which first established Troy weight as the only legal 



weight for gold and silver, and from this time to the pre- 

 sent our system of coinage has been based on the Troy 

 weight, the Troy pound containing 5760 grains. 1 



The bullion transactions of the Mint have hitherto been 

 based on an Assayer's weight termed the "carat pound," 

 the final division of which corresponds with the number 

 of grains in the Troy pound, and side by side with this 

 system a curious method of expressing the ' standard ' or 

 composition of ingots or coins of gold and silver has been 

 retained until the present year. For instance, the ordi- 

 nary conception of the composition of a sovereign would 

 be that it is an alloy or mixture of the two metals gold 

 and copper in definite proportions, and the most simple 

 way of expressing its contents would be to describe them 

 as consisting of (J,r66 per cent, of gold and 834 per cent, 

 of copper. An assayer or bullion dealer, on the other 

 hand, using the old system, would simply consider the 

 composition of the coin to be gold of ' standard fineness,' 

 that is to say, containing two carats of alloying metal in 

 the pound ; and in dealing with any particular alloy of 

 gold and copper would in no way regard its per-centage 

 composition, but would consider it as being so much 

 "better" or "worse" than the one definite and legal 

 standard, according as it contained more or less of the 

 precious metal. The French 20-franc piece, which con- 

 tains 90 per cent, of gold, would thus be described as 

 " worse o carats if carat grains," and an Austrian ducat, 

 which contains 9861 per cent, of gold, as " better 1 carat 

 2jj carat grains." The cumbersome nature of this system 

 is evident ; it has the disadvantage of being unintelligible 

 to those who employ the decimal system, and who are 

 therefore in the habit of mentally referring to pure gold 

 as 1000 It is even found wanting in clearness by many 

 who are conversant with the ordinary operations of coin- 

 age and bullion transactions generally. For instance, 

 the meaning of " worse o if + 1 '' as the assay report of 

 an ingot is at least obscure, while the equivalent state- 

 ment that the standard fineness of the ingot is 900 at 

 once suggests that 1000 parts of the metal contain 900 

 parts of gold. 



The ancient system of reporting the results of assays 

 possesses however many points of interest, and Prof. 

 Roberts adds a few details respecting it, taken from a 

 work by Snelling,- an authority on the computation of the 

 value of bullion, who, writing in 1766, observes that "by 

 the word silver we understand not only the metal so- 

 called, pure and unmixed, but also when in a mass with 

 copper ; and if but one-half, two-thirds, or any other pro- 

 portional part of it be silver, yet the whole bears that 

 name. The same is to be understood of gold, when by 

 itself, or in a mass with silver and copper together, or 

 with either of them alone." 



"This is the reason that inquiries are not made, what 

 quantity of fine gold or fine silver is contained in any 

 mixture, which seems to be the most natural inquiry, but 

 how much standard it holds." Thus it is that " the 

 Assay Master, in reporting the result of an assay, does 

 not give the absolute fineness or the quantity of fine silver 

 or fine gold present, but only the relative quantity or 

 fineness, that is, how much the mixture is more or less 

 than standard. In the case of gold of 20 carats fine (or 

 20 parts of pure gold in 24 parts of the alloy) the assayer 



puts down Wo. jj ' and if it is 23 carats 3i grains fine, 



he puts down Br. C ? ' Aj' oh." The last sign represents 



an obolus or half of a carat grain, but in modern times 

 the final division has been i/6oth of a carat grain. 



It may be pointed out in defence of this complicated 

 system, that, as Snelling proceeds to remark, " the quan- 



» " On the Abolition of the Troy Pound," the third Report of the Com- 

 missioners appointed to inquire into the condition of the Exchequer Standards. 

 Parliamentary paper [c. 30J, 1870. 



2 " Doctrine of Gold and Silver Computations," by Thomas Snelling. 

 (London, 1766.) 



