ca ile 
De. 7, 1882 | 
NATURE 
13a 
more complete demonstration a good deal further illus- 
trating the actual movement, has to be said on that head. 
Here we have space only for a general outline. 
The muscle, of course, has no isolated voluntary 
action, but its effect is brought into play when the eye- 
brows are forcibly raised by the contraction of the occi- 
pito frontalis. Indeed, although itseif really a muscle as 
described, much of its effect is derived after the fashion 
of an elastic tendon connected with the great epicranial 
muscle. It is further assiste1 by the consentaneous 
action of certain small muscles of the auricle, notably the 
attollens auriculam. Its movement is quite perceptible 
to the finger placed in the sulcus, between the pinna and 
side of the head, and to an experienced eye its effect on 
the membrane is distinctly visible through the speculu n 
when the occipito-frontalis is mide to contract. 
It would be beyond the scope ofa single paper to enter 
into a demonstration of the effect of this movement of 
the membrana flaccida on the membrane and ossicles— 
but it can be shown that, in opposition to the so-called 
tensor tympani muscle, it helps to bring the umbo or 
deepest part of the membrane outwards, thus tending to 
reverse the cone, and bring the membrane generally into 
a more vertical position, relatively to the lower wall of 
the meatus. This is beyond all question its position for 
acutest hearing, and it is thus important to observe that 
by the single contraction of the occipito frontalis muscle, 
both eyes and ears are brought simultaneously into the 
attitudes of strained attention. Hence, in endeavouring 
to hear as well as to see intently, we involuntarily raise 
the eyebrows in order t> tell upon the drum of the ear. 
A smart blow administered on the side of the head, as 
is too often thoushtlessly done by schoolmasters and 
parents in correcting children, may cause sudden spas- 
modic action of the muscle, and thus, through the action 
of the mechanism described, serious injury or even 
rupture of the drum. JOHN M. CROMBIE 
WEIGHTS AND MEASURES 
oe Board of Trade lay before Parliament an Annual 
Report of their proceedings and business under the 
Weights and Measures Acts, &c., and their Report for 
the current year has just been issued. 
It is required by law that the three Parliamentary 
copies of the Imperial Standards of measure and weight, 
which are deposited at the Royal Mint with the Royal 
Society, and in the Royal Observatory, respectively, 
should be compared with each other once in every ten 
years. The period for such decennial comparisons 
having recently arrived the Board took the necessary 
steps for the removal of these Standards to their office. 
The methods of comparison adopted and the actual dif- 
ferences between the Standards are shown in a memo- 
randum by Mr. H. J. Chaney, which is attached to the 
Report. It appears that the comparing apparatus in use 
at the Standards Office is found to require alteration, a «| 
that in considering the changes necessary to be made the 
Board have hai the valuable assistance of a Committee 
of the Royal Society, composed of Sir G. Airy, Major-Gen. 
A. R. Clarke, and Prof. Stokes. It is really important 
that a department which is charged with the care and 
use of our national standards, should have the best appa- 
ratus, and we trust, therefore, that the Report of the 
Committee may be speedily and fully carried out. 
Reference is also made to the papers issued by the 
Comité International des Poids et Measures, Paris, aud 
the Report acknowledges the assistance the Standards 
Department has received from these papers, particularly 
with reference to the measurement of heat and the deter- 
mination of volume and weight. This country is the only 
civilised country which has not joined the Comité Inter- 
national, and taken part officially in their proceedings, 
although it would appear that it has not failed to avail 
itself of their labours. 
The two ancient standards of the metric system, the 
Toise du Perou and the Toise du Nord, are stated to be 
still at the Paris Observatory, in a good state of preser- 
vation, as also are the measures used by Borda, Brisson, 
and Lavoisier. By a decree of the Sultan, the metric 
system came into force in Turkey on March Ist last, and 
the equivalents of the old and new Turkish weights and 
measures are stated ia this Report. 
The Board have had their attention cirected to the 
question of a uniform system of screw threads, as well as 
to that of a standard wire gauge. Reference is made to the 
want of uniformity in the system of screw threads used 
in the construction of scientific and optical instruments. 
It is hoped that the attention which is now being given to 
this question may result in the adoption of a standard 
syst-m of screw threads. Any step which tends to lessen 
the high cust of construction and of repair of scientific 
apparatus is to be welcomed. 
From time to time, as science advances and commerce 
extends, it is found that new kinds of standards are 
needed, and the attention of the Department has there- 
fore been this year called to the expediency of adopting 
new photometric tests for gas, and also as to possible 
means of measuring electrical energy. In the proposed 
Bill for amending the enactments for regulating the sale 
of gas, and of dealing with the mode of testing the illu- 
minating power of gas, we trust that Mr. Vernon Har- 
cour’s new air gas-flame test, on which Dr. Williamson 
and Dr. Odling have reported, may receive favourable 
consideration. 
Under the Petroleum Acts rules are laid down for 
determining the “flashing-point’’ of oils, or the tem- 
perature at which they begin to give off inflammable 
vapours, but it appears by the Report that Dr. Foerster 
has lately called attention to the omission in these rules 
of any allowance for variations of atmospheric pressure. 
The rules in this respect evidently, therefore, require 
some amendment. 
The Report also contains much information valuable 
to local inspectors and others practically interested in 
weighing and measuring. 
ON THE PROPOSED FORTH BRIDGE 
\2 offering some remarks (which I trust may be final) 
merely explanatory of preceding notes on this pro- 
posed structure, I shall refer generally to my letter of 
October 19 (NATURE, vol. xxvi. pp. 598-601). 
First, I have to modify the force of my expressions re- 
lating to the danger arising from the use of certain long 
struts to support very heavy end-pressures. My remarks 
were the consequence of error in the engraved longi- 
tudinal vertical plain, circulated (I understood) under the 
authority of the Official Board. In this plan, by the in- 
discretion of the engraver, the tubular struts of 340 feet 
| length and 240 feet length respectively, are drawn clearly 
vnd distinctly as unconnected in their entire length with 
auy other braces. In other parts of the plan, each con- 
nection of that class is indicated by a rose ; but there is 
no such mark upon these rods. A person scrutinising 
the plan m‘ght well feel alarm at the prospect of unbraced 
rods 340 feet long, intended to support end-pressures ex- 
cezding 600 tons. But Mr. Fowler has kindly informed 
me that the plan is erroaeous, and that there is connection 
at each place where the strut crosses a brace, and that 
the flexible length of the strut is thus reduced to 170 feet. 
This diminishes the danger of buckling in a vertical 
plane so greatly that I imagine it may be passed without 
further notice. Still I remark that the danger of buckling 
in a horizontal direction, with a length of 340 feet, re- 
mains undiminished, unless it is counteracted by bracing 
not known to me. 
In regard to some effects of the wind, the following 
comparison between the proposed Forth Bridge and the 
