**In this topic,** I present the fully compensated averaged scans obtained in the two observing periods, 1971 and 1972, for all observed elongations, each with a fitted Gaussian curve, except as noted. From parameters derived from these fits, plots of average wavelength shift, line width and line depth against elongation are constructed. These observations, the Hicks and Reay (HMR) data, are compared with previous and all subsequent observations since 1974, and examined with reference to the predictions of various models. The models are based on various distributions of dust moving in prograde and retrograde solar orbits, and a new model is presented of interstellar material flowing through the Solar System. A geocentric component, and the effects of distant emitting matter are also considered. New theoretical models by various authors since 1974 are examined and compared with the data. Theories are advanced as to why there might be seasonal variations in the radial velocities measured in the Zodiacal Cloud (ZC).

## Gallery of Spectra

**They show intensity** plotted against wavelength for all targeted elongations, in the two observing periods, September-October 1971, and April 1972. For ease of comparison, the two sets of data are matched side by side according to elongation. For most spectra, a Gaussian curve was satisfactorily fitted by the method of least squares, as described in topic 3, and is shown in the relevant graph. In four cases, where the continuum levels were very different on each side, no Gaussian fit could be obtained, and for these, a polynomial fit was used instead. Some scans were performed over a wider wavelength range than 5 A, but for consistency only the central 5 A were used for this analysis. In any case, the extreme outer wavelengths were observed at low transmission of the broad interference filter, and, hence, being subject to large random errors, would not have improved the fits.

**FULLY CORRECTED SCANS**

**with fitted Gaussian curves, except where otherwise stated**

**FULLY CORRECTED SCANS**

**with fitted Gaussian curves, except where otherwise stated**

**FULLY CORRECTED SCANS**

**with fitted Gaussian curves, except where otherwise stated**

**FULLY CORRECTED SCANS**

**with fitted Gaussian curves, except where otherwise stated**

**FULLY CORRECTED SCANS**

**with fitted Gaussian curves, except where otherwise stated**

**FULLY CORRECTED SCANS**

**with fitted Gaussian curves, except where otherwise stated**

**FULLY CORRECTED SCANS**

**with fitted Gaussian curves, except where otherwise stated**

**FULLY CORRECTED SCANS**

**with fitted Gaussian curves, except where otherwise stated**

**FULLY CORRECTED SCANS**

**with fitted Gaussian curves, except where otherwise stated**

**FULLY CORRECTED SCANS**

**with fitted Gaussian curves, except where otherwise stated**

**Figure 4.0 Example of an unrealistically wide fitted Gaussian curve, in this case corresponding to ‘rogue’ point (a) in Fig 4.1.**