454 



KNOWLEDGE & SCIENTIFIC NEWS. 



[June, 1906. 



difference between the two numbers composing the ratio 

 is an even number, such as i : 5, 3 : 7, or 3 : 5. On the 

 other hand 1:2, 1:4, 2:3, and any ratio where the 

 difference is an uneven number, give harmonies which 

 are non-symir.clrical. 



Approximate l : 3 harmony (opposed rotation) traced 

 miniature twin°elliptic pendulum. 



To start the instrument hold the rod near the top and 

 give it a slight circular movement followed by a very 

 slight reverse impulse. This will start the two pendu- 

 lums in opposed rotation. A single impulse will start 

 them in concurrent rotation. 



Fig. 2.— Miniature Harmonograpli (Tisley typel. The paper strip 

 with needle is attached to the pendulum on the right and 

 is supported by a silk thread hanging from the wire on the 

 left, which lowers the needle for describing the curves, the 

 silk then hanging loose. As shown, the weights are adjusted 

 for the harmony 1 : 3. 



To tune the instrument, adjust the upper pendulum 

 weight to various positions until an approximate 

 harmony is reached. If the repeat line ialls in advance, 

 raise the upper weight a little ; if it lags behind lower the 

 upper weight. The weight on the lower pendulum may 



be raised and lowered with similar effects, but in a less 

 marked degree, so that it is only necessary to alter it for 

 fine adjustment. 



The ratios of the harmonies obtained are thus com- 

 puted : With concurrent movement the nodes (i.e., loops 

 or points) are inside the figure and their number is the 

 difference of the numbers in the ratio. With opposed 

 movement the loops are outside, and their number is the 

 sum of the numbers in the ratio. For example, if with 

 concurrent rotation there are eight internal nodes, while 

 with opposed rotation there are 14 external loops, x-|-y 

 = 14 ; X — y = 8. 84-2y = 14, y = 3, x= 1 1, or the ratio is 



Fig. 2 shows an ordinary harmonograph of minia- 

 ture form, which by means of the paper strip device 

 gives very fine tracings, though the weights are no 

 heavier than those in the miniature twin elliptic. By 

 using a top-weight harmonies of i : 3 can be obtained 

 with this little instrument. Two specimens of its work 

 are reproduced. 



A similar recorder would probably be very service- 

 able for seismographs, and for any purpose which 

 involves the registering of minute oscillations. 



.^^^^^^^ 



Queensland Message 

 Sticks. 



A GOOD deal of uncertainty and a large amount of specu- 

 lation surround the methods by which the members of 

 aljoriginn! races communicate one with another. 

 N'umerous legends have collected about the so-called 

 message-sticks of the Queensland natives, which have 

 been said to serve the piirpi-se of conveying messages 

 from one part of the colony to another among the 

 natives. .Some authentic explanatiim on the point 

 is supplied by Mr. Walter Roth in Hullrtin Xo. S — 

 North Ouecnsland Ethnography, which is published by 

 the Ouecnsland Ciovcrnment. Mr. Roth writes : — 



" the limited quantity and portability of a native's 

 personal goods offer little or no opportunity for the use 

 I if property-marks. If weapons are of the same cut, 

 there are minute, yet sufTicient, differences which arc 

 recognisable to the owners ; even if similarly orna- 

 meutcd, no two are so alike that they cannot be dis- 

 tinguished. In a general wa}', each having sufficient 

 for his own wants, and no person having more than 

 .•mother, there is nothing to thieve, and hence, as al- 

 ready mentioned, the levity with which theft, even 

 when it occurs, is regarded. Only in cases of trade 

 .ind barter, through an intermediary, where it is essen- 

 tial that one individual's goods should be distinguished 

 from another's, is there a necessity for a definite pro- 

 perty-mark, this taking the form of a so-called ' letter-' 

 or ' message-stick.' Under such circumstances, the 

 ' stick ' may be put into use as follows : — Charlie, re- 

 siding at Boulia, wants, we will say, some pituri, but 

 being prevented by sickness or some other cause from 

 going himself, sends some relative or friend Peter to 

 the nearest market, on the Mulligan River, to get some 

 for him, and gives him a 'message-stick.' Arrived 

 at last at his destination, Peter is asked his business, 

 tells who has sent him, hands over the ' stick,' and 

 establishes his bond fides. The bagful of pituri being at 

 last forthcoming, the vendor returns the ' stick ' to 

 Peter, but not before taking careful mental note of it, 



