It is interesting to compare crochet methods of the past with those we use today. In the period 1824 to 1833, for instance, it is documented in the Dutch magazine, Penelope, that both the yarn and hook were to be held in the right hand and the yarn passed over the hook from the right forefinger. In crochet books from the 1840s, the hook is held in the right hand and the yarn in the left, as right-handers do today.
In a German publication dated 1847, it stated that one should always "keep the same tension, either crochet loosely or crochet tightly, otherwise an attractively even texture will not be achieved. Moreover, if not working in the round, you have to break off your yarn at the end of each row, since this gives a finer finish to the crocheted article." Today's patterns, thank goodness, usually instruct us to work both the right and wrong sides of the fabric we are creating. This change came about at the turn of the 20th century.
Researcher Lis Paludan speculates that the admonition to keep the same tension "seems to suggest that crochet hooks were of the same thickness and that the crocheter was expected to work in the correct tension according to the pattern."
Old pattern instructions, dating about the mid-1800s, indicated that the hook was to be inserted into the back half of the stitch only, using a single crochet stitch unless otherwise instructed. Jenny Lambert, a European, wrote in 1847 that inserting the single crochet into the back half of the stitch was useful for making table runners and such, but inserting the hook through both loops could be used "to crochet soles for shoes and other articles which have to be thicker than average, but the technique is not suitable for patterns." Today, of course, unless told to do otherwise, we automatically go through both loops.