summarized in Table 1. In the initial test series the 38-millimeter ball 
vibrators were found to be inadequate and the remaining tests were conducted 
with the 64-millimeter ball vibrators and the 3-inch piston vibrator. In 
general, the deepest penetration with the larger vibrators were obtained in 
fine-grained sediments such as mud, silt, and clay. The corer penetration 
was least in areas underlain by glacial till. Results in sand varied, but 
most of the cores recovered 1 to 2 meters of sediment. The cores that were 
split for detailed examination showed little disturbance or distortion of 
thin-bedded sequences. 
As a result of the field tests, a final design was selected which con- 
sisted of the small frame extended to an overall length of 3 meters to allow 
for a 2.4-meter core barrel. The 3-inch piston vibrator was chosen over the 
64-millimeter ball vibrators because at a given location it gave nearly the 
same results while requiring significantly less air, allowing the use of a 
smaller compressor and two instead of four hoses (see Table 2). Drawings and 
a description of the final design are provided in the following section. The 
slide section was modified after the field test to eliminate the plate used to 
attach the ball vibrators, thus allowing for a longer core barrel. The ‘ 
figures and drawings herein show the device after final rodification. 
III. DESCRIPTION OF CORING ASSEMBLY 
1. Frame. 
The frame of the lightweight pneumatic corer is constructed of standard- 
size structural aluminum and consists of four main sections: the base, the 
cap, the slide, and the upright guide pipes. The overall length, and thus 
the length of the core tube, can vary by using shorter or longer guide pipes. 
The design drawings show 3-meter-long guide pipes. 
The base section (Fig. 4) is 48.5 inches square and constructed of alumi- 
num channel and angle. The central crossmember is an aluminum channel with a 
centered 3.5-inch hole to allow passage of the core tube. On either side of 
the hole are 4-inch pieces of nominal 2.5-inch aluminum pipe, welded in an 
upright position to serve as sockets for the guide pipes. The guide pipes 
are equal lengths of nominal 2-inch aluminum pipe of the desired length. 
The guide pipes are surmounted by a cap section (Fig. 3) consisting of a 
length of channel with two 4-inch-long pieces of nominal 2.5-inch aluminum 
pipe welded to the inside to serve as the upper sockets for the guide pipes. 
A central hole in the cap allows passage of the retrieving cable. The base, 
guide pipes, and cap are held together and braced by four pieces of nominal 
0.25-inch steel cable attached with clevises and turnbuckles extending from 
the four corners of the cap section to the four similar corners of the base 
section (Fig. 2). 
The slide section (Fig. 4), which holds the vibrator and the core barrel, 
consists of two vertical 13-inch pieces of 2.5-inch aluminum pipe joined by 
two 17.5- by 5-inch pieces of 0.25-inch aluminum plate. The vibrator is 
sandwiched between the two plates. The vertical pipes at either end slide up 
and down the guide pipes. Bolted to the bottom of the slide plate is a nominal 
