We have investigated a group of 18 Algol-type binaries to determine the general morphologies and physical properties of the accretion regions in these systems. The systems studied were V505 Sgr, RZ Cas, AI Dra, TV Cas, TW Cas, d Lib, RW Tau, TW Dra, b Per, TX UMa, U Sge, S Equ, U CrB, RS Vul, SW Cyg, CX Dra, TT Hya, and AU Mon, in order of increasing orbital period P \ 1.18È11.11 days. In addition, the RS CVn-type binary HR 1099 (V711 Tau) was observed to illustrate the appearance of chromospheric Ha emission. Nearly 2200 time-resolved Ha spectra were collected from 1992 March to 1994 December with the McMath-Pierce Solar Telescope at NSO and mostly with the Coude Feed Telescope at KPNO. The spectra were obtained at phases around the entire orbit of each binary and were closely spaced to permit the detection of transitions in the proÐles. Moreover, the spectra were obtained typically within three orbital cycles to reduce the inÑuence of secular variations. Di †erence proÐles were calculated by subtracting a composite theoretical photospheric spectrum from the observed spectrum.The analysis of the Ha di †erence proÐles demonstrates that the accretion structures in Algol binaries have four basic morphological types : (1) double-peaked emission systems in which the accretion structure is a transient or classical accretion disk ; (2) single-peaked emission systems in which the accreted gas was found along the trajectory of the gas stream and also between the two stars in an accretion annulus ; (3) alternating single-and double-peaked emission systems, which can change between a single-peaked and a double-peaked type within an orbital cycle ; and (4) weak spectrum systems in which there was little evidence of any accretion structure since the di †erence spectra are weak at all phases. The Ðrst two types are the dominant morphologies. The Ðrst type can be interpreted physically as a disklike distribution, while the second is a gas streamÈlike distribution.The most common type in short-period Algols with 2.7 days \ P \ 4.5 days is a predominantly singlepeaked emission feature in the Ha di †erence proÐles (Type 2). This feature is redshifted during the phase interval / D 0.15È0.45 and blueshifted from / D 0.55È0.85. This single-peaked emission is often composed of two closely spaced emission peaks where one peak is at the Ha rest wavelength. The other peak is blueshifted at / D 0.65, where the line of sight is along the length of the approaching gas stream. Systems which display this morphology include RZ Cas, RW Tau, TW Dra, b Per, TX UMa, S Equ, and RS Vul. The orbital variation of the Ha observed proÐles of HR 1099 was similar to that seen in the di †erence spectra of this group and suggests that chromospheric emission may play a signiÐcant role in these binaries. A less common morphological type in the group of short-period Algols was a widely separated double-peaked disk-like distribution (Type 1) where the gas is in a transient or classical accretion disk. All of the long-period systems (P [ 6 days) were f...

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