Inclination Measurements Research Articles

The Palaeogeographic Latitude of Oil-fields

Summary From a study of the magnetism of a rock sequence the palaeogeographic latitude at the time the beds were laid down may be estimated. Little work of this type has been reported from actual oil-fields but useful results can be obtained by extrapolating from magnetic data already recorded from nearby regions. The palaeolatitudes of many pre-Tertiary oil-fields obtained by these methods are shown to be usually less than 20° although their present latitudes range from 25° to 59°. These results are consistent with the hypothesis that oil originated preferentially in low rather than high latitudes. They also suggest that the measurement of the magnetic inclination in rock sequences which are being explored for oil is a useful tool for deciding the likelihood of the occurrence of oil.

Relationship of various skull reference lines

Cephalometric roentgenograms from 87 male dental students were analyzed. The nasion-sella line, the Frankfort line, the Camper line, and the occlusal line of the maxilla were marked on tracing paper. The average angles between these lines were calculated, and the angles were ranked according to the magnitude of the variation. Measurements of condyle path inclinations in relation to some reference lines can be roughly “translated” with regard to other reference lines by means of these average angular values. It is also possible to compare the indications of mean value condyle path inclinations with those of other investigations.

Roentgenostatics: A practical evaluation of the x-ray headplate

In this relatively brief résumé of my extensive study of roentgenostatics, I have tried to demonstrate the insight into many orthodontic problems that is supplied by the headplate. With some of the diagnostic criteria that I have developed, more precise information concerning orthodontic therapy is available. Gnathometry has proved to be the most important part of the headplate analysis, and I believe that it will play the leading role in the future. It completes and often corrects previous diagnostic impressions derived from examination of the patients, casts, and dental radiographs. Used properly, it makes available valuable guides for treatment and an exact cosmetic prognosis. The greatest advantage of gnathometry is the examination of the dentition itself, independent of craniometric considerations. Fundamental errors in interpretation must occur if the details of malocclusion are related to outside craniometric reference lines or points. An example of this is the measurement of the axial inclination or position of the maxillary incisors in relation to the horizontal Frankfort plane or to the nasion-sella plane. Consideration of the individual jaw inclination and the temporomandibular joint position must be made before malpositions of the teeth in the dentition itself are measured and interpreted. Some techniques which ignore this fundamental consideration also disregard the individual natural skull architecture. Faulty interpretations are made which even decades of clinical experience will not prevent. Particularly in Class II, Division 1 and Class III malocclusions, in bimaxillary protrusions, and in problems involving the extraction of premolars, the cephalometric headplate has proved essential at the time for decision. A major challenge still confronts the orthodontist. He must know to what extent he can influence the morphologic symptoms of a malformation with the therapeutic measures that he has under his control. Cephalometrics will undoubtedly help him delineate the limits of his endeavors.

New Dip-Logging Method

This paper describes a new method of determining the dip and strike of subsurface formations in the earth from measurements taken in a single bore hole. The method is based on the fact that the drilling process erodes some formations more than others. A log is made of three simultaneous profiles of the bore-hole wall which are oriented with respect to compass north. These profiles enable measurements to be made of the vertical displacements of the edges of hard strata protruding into the bore hole. From these measurements and from continuous measurements of inclination and direction, the dip and strike of the subsurface formations can be calculated. An extensive field-testing program has proved the principles involved to be sound. During this field work, dips ranging from zero to 75° were measured. It was found possible to re-log a given well and reproduce approximately 70 per cent of the final dip results within 2°. From such results it is concluded that the profile method of measuring the dip of subsurface formations is sound and of considerable value in the study of subsurface geology.

Preliminary results of magnetic measurements at the “North Pole” station

We took magnetic measurements with the aid of a theodolite and also diurnal series of measurements of the magnetic variations using special visual magnetometers. A total of 55 measurements of declination and of horizontal intensity and 36 measurements of inclination were made.Up to the middle of November, 1937, 14 diurnal series of measurements of variation were made, but later the ice‐floe began to turn around hindering the use of the variometers. As a result of measurement of the variations it was observed that the declination had an average diurnal value at about 6h, 13h, and 0h, GMT; between 6h and 13h the deviation was to the east, between 13h and 0h to the west, and between 0h and 6h a little to the east; these characteristics persisted in all cases. The amplitude ranged from 2° on quiet days to 10° on disturbed days. The horizontal intensity had an average diurnal value at about 6h, 10h, and 18h; a small maximum was observed from 6h to 10h, a large minimum from 10h to 18h, and a large maximum from 18h to 6h. In the main this character persisted. The amplitude ranged from 150 to 500 gammas.

Magnetic and electric observations of the Drift‐Expedition to the North Pole

An important place in the program of work of the Expedition to the North Pole is given to the study of the magnetic and electrical phenomena. Absolute determinations of the magnetic elements will be made with Chasselon theodolite No. 87, adapted for measurements in high latitudes. The declination will be determined by the usual method, and the inclination by the Lamont‐method using rods of “dynamo” steel. Two pairs of rods of different sizes will secure a measurement of inclination up to 88°.

The Measurement of Altitude and Inclination of Aircraft by the Echo Method

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On observations of magnetic anomalies with a variometer

The accuracy of determinations for magnetic anomalies in horizontal intensity, H, and vertical intensity, Z, using the author's variometer, is now as good as that obtained by absolute measurements. The variometer can be used accurately without resetting for determinations on lines as long as 300 kilometers in the north‐south direction. The question as to whether local anomalies may be affected by secular variations is discussed theoretically. An attempt to check the theory developed using previous observations of intensity gives no definite conclusions; absolute measurements of inclination with the dip‐needle are not of sufficient accuracy to give a reliable test. In the study of a deep‐seated regional anomaly and in the preparation of land magnetic charts, it is found best to discard all values at stations where the adjacent rocks have differences of susceptibility of more than 2×10−4.

Earth‐inductor measurements aboard the Carnegie, Cruise VII

On the recently ended last cruise of the non‐magnetic vessel Carnegie the earth inductor was used for the routine measurement of inclination and, experimentally, for the measurement of the horizontal intensity of the Earth's magnetic field.

Earth‐inductor measurements aboard the Carnegie, Cruise VII

On the recently ended last cruise of the non‐magnetic vessel Carnegie the earth inductor was used for the routine measurement of inclination and, experimentally, for the measurement of the horizontal intensity of the Earth's magnetic field.

The theory of the Earth inductor as an inclinometer

The earth inductor, in its most complete form, as used for the measurement of the magnetic inclination, consists essentially of a coil (Crpar; of insulated wire which can be rapidly and continuously rotated about an axis (ABrpar;, Fig. 1, which coincides with a diameter of the coil. The axis AB is capable of measured rotation about the two mutually perpendicular axes, one horizontal, DE, and the other vertical, V; by construction AB is perpendicular to DE. Thus the direction of AB can be made to coincide with that of any radius of a sphere having its center at the intersection of the three axes. In the future we shall speak of AB as the axis of rotation, of DE as the inclination axis, and of V as the azimuth axis, and shall call the plane which includes both AB and DE the “inclined plane” of the instrument.