Trachydolerite in Tasmania

In 1889 evidence was laid before this Society by Mr. W. F. Petterd and myself, demonstrating the existence in Tasmania of two centres or districts characterised by eruptive rocks derived from elaeolitic and theralitic magmas. I now submit further localities for rocks belonging to the same great felspathoid series. One of these is the Table Cape Bluff, near Wynyard, on the North-West Coast, and another is the Nut at Circular Head. A third is One Tree Point, Sandy Bay, near Hobart, where melilite, basalt has been identified, but only the first two will be dealt with in these notes

Discovery of an aboriginal chipped flake in deep ground near Gladstone

I happened to be at Gladstone last March when a worked stone of chalcedony was brought to me as a strange specimen found by Mr. Richards in working Richards's and Murray's alluvial tin claim at the old Doone mine, north of the Ringarooma River, and two miles from Gladstone. I recognised it as an aboriginal Flake, but, to make sure, I submitted it to Mr. R. M. Johnston, whose knowledge of these implements is unrivalled, and lie at once pronounced it to be of human workmanship. The following day I proceeded to the claim in order to examine the conditions of occurrence. The actual block of gravel from which the stone had been picked had disappeared in sluicing, but I stood on the actual site of the discovery, and Mr. Richards, who enjoys a high reputation for reliability and integrity, explained to me all the attendant circumstances

Reduced Major Axis Regression: Teaching Alternatives to Least Squares

The theoretical underpinnings of standard least squares regression analysis are based on the assumption that the independent variable (often thought of as x) is measured without error as a design variable. The dependent variable (often labeled y) is modeled as having uncertainty or error. Both independent and dependent measurements may have multiple sources of error. Thus the underlying least squares regression assumptions can be violated. Reduced Major Axis (RMA) regression is specifically formulated to handle errors in both the x and y variables. It is an excellent topic to teach students the importance of understanding the assumptions underlying the statistical procedures commonly used in practice as well as showing them that alternatives may better satisfy the actual needs

Rehabilitation of deteriorated timber piles with fiber reinforced composite wrap systems

Fiber reinforced polymer (FRP) composite wraps have been used for timber pile repair, but there is a lack of empirical data for the development of design guidelines and strengthening equations. To address this need, this study evaluated both the bond and compressive strength of four FRP wrap systems on whole timber piles. Wrap systems evaluated used glass fabric with epoxy, polyurethane, and phenol formaldehyde resins. Bond strengths were evaluated through push-out and pull-off bond testing data on new (unused) treated timber. The push-out test evaluated the bond strength of the wraps on timber by applying axial loads on wrapped (6 and 12 bond lengths) timber samples until bond slippage occurred. Modified pull-off tests ASTM D7522, (FRP wraps on concrete substrates), were conducted to establish pull-off bond strengths. Axial compression tests were performed on hand layup shells with varying numbers of wrap until failure. To evaluate bond strength and compressive capacity simultaneously, simulations of timber pile rehabilitation were performed also. For the simulations, two portions of timber separated by a gap (to simulate decayed timber with near zero strength) were wrapped and tested in axial compression until failure. Results revealed that while 12 bond lengths provided a higher capacity than 6 bond lengths, their bond strengths (P/A) were reduced suggesting a non-linear relationship between bond strength and bond length. Epoxy and phenol formaldehyde resin systems predominately displayed timber failure whereas the polyurethane system failed in bond. Systems that utilized slow cure, low-viscosity resins developed high bond strengths, suggesting good timber penetration. Compression evaluations showed additional wrap layers increased the compression capacity of the shells. Some shells developed bending moments from unintended eccentric loading which reduced compressive capacity. Epoxy and phenol formaldehyde systems failed in the fibers while the polyurethane system failed due to delamination. Systems with high fiber volume fractions in the axial direction displayed the highest axial capacity. Compressive strength results corresponded well with values predicted by mechanics based FRP design equations. Since no current models for FRP bond strengths on timber are available, these results will greatly aid in their development