Opsonic Index. 



Mr. Johnston read a paper by Dr. E. 

 J. Roberts on "The Germ as a Friend in 

 Therapoiitics" (Opsonic Index.) The 

 paper dealt larjjely with the investiga- 

 tions which have been made for the pur- 

 pose of determining wliat might bo 

 called the strength of an antitoxin for 

 combating an infections disease as ft 

 occurs in a particular patient. 



Dr. EJkington.the Chief Health Officer 

 favoured the society Avith some remarks 

 on Dr. Roberts's paper. 



* Mr. Glblln was good enough to name the 

 tor crowning the high ridge of the fells he 

 ascended Mount Legge, In lionour of my 

 leadership of the expedition to find the alti- 

 tude of the northern area of the plateau 



THE BEN LOMOND RANGE. 



NOTE ON THE HEIGHT OF LEGGE 

 TOR. 



•3v Meesrs. L. F. Giblin, B.A., and E. 

 L. Pie&se, B.Sc, read June 11, 1907.) 



During two visits to the Ben Lomond 

 Range in March, 1906, and March, 1907, 

 we made some observations of the height 

 of the northern part of the range, 

 which we wish to bring to the notice of 

 the society. On both occasions our par- 

 ties were under the guidance of Colonel 

 Legge, who has frequently visited the 

 range, and who has given a full descrip- 

 tion of it in a paper read at the last 

 meeting of the Australasian Association 

 for the Advancement of Science. It was 

 at his suggestion that we made the ob- 

 servations we now describe. 



The most conspicuous feature of the 

 Ben Lomond Range is the south-western 

 summit, surrounded on two sides by high 

 diabase clifits, which is seen from the 

 main line railway for many miles. On 

 this summit is situated one of the sta- 

 tions of the Trigonometrical Survey of 

 Tasmania made in 1851 and the 

 following years. The maps of Tas- 

 mania based upon this survey, show 

 tht height of this station to be 5,010ft., 

 and it has usually been thought to be 

 the highest point of the range, and 

 the highest point in Tasmania, with the 

 sole exception of Cradle Mountain, which 

 is stated on the maps to be 5,069ft. high. 

 It should, however, be mentioned in dis- 

 cussing the heights of our highest moun- 

 tains that no exact observations seem to 

 have been made for the height of Barn 

 Bluff, which is over 5,000ft. 



F/Ooking northwards from the Trig- 

 onometiical Station, the range is seen to 

 extend for seven or eight mileH, with a 

 width of three or four miles. A wide and 

 deep valley, called by (-olonel Legge the 

 Dividing Valley, separates the summit 

 into two areas of noticeably different 

 character. The southern portion may 

 be roughly described as a plateau, inter- 

 sected l)y shallow and wide valleys, lying 

 from 500 to 1,000 feet below the summit 

 before mentioned, which rises out of the 

 plateau at its south-western corner. The 

 northern portion is much more broken 

 in appearance, and its average height is 

 much greater than that of the southern 

 half of the mountain. In the centre of 

 the northern half, about one and a half 

 miles distant from the noi'thern, eastern, 

 and western escarpments of the range 

 lies the summit which is the subject of 

 this note. From the trigonometrical 

 station this summit appears to the un- 

 aided eye to be the highest point of the 

 mountain. Our observations were made 

 to determine the difference of height be- 

 tween the trigonometrical station and 

 the northern summit. For this purpose 

 we used in the first instance an aneroid 

 barometer, and subsequently we obtain- 

 ed a rough check from observations with 

 an Abney level. We are aware of the 

 many sources of error incident to the 

 use of aneroids, but the instrument used 

 was a good one, and most of the observa- 

 tions were made in good conditions, and 

 we therefore think the results are worth 

 publishing. 



The comparison of heights was made in 

 three stages. In the first place we 

 found the height of Colonel Legge's camp 

 at Broken Bluff, at the south-eastern cor- 

 ner of the mountain, near Col. Legge's 

 thermometrical station, and a short dis- 

 tance from the end of the track from 

 Mangana. Taking the mean of ascend- 

 ing and descending readings (which is the 

 method recommended by Mr. Edward 

 Whymper in his paper, "How to use the 

 Aneroid Barometer"), and correcting for 

 a fairly uniform change of pressure 

 which was taking place during the 

 day, we found that Broken Bluff 

 camp was 710 feet below the trigonome- 

 trical station. In 1906 the instrument 

 used this year, and another instrument, 

 each gave 720 feet for this stage. The 

 height of Broken Bluff camp is there- 

 fore about 4,300 feet— a result probably 

 correct within 20ft. or 30ft. unless some 

 hidden source of error was present on 

 each occasion. 



The next stage was from Broken. Bluff 

 camp to a second camp at Meadow Vale, 

 a grassy valley in the northern portion 

 of the range, four or five miles frono. 

 Broken Bluff. From our obeervatioois on 

 March 16, we found that Meadow Vak 

 was 400ft. above Broken Bluff. We mad* 



