HEL 



HEL 



manner of examining these eyes, which 

 are four in number, is this : when the 

 horns are out, cut off nimbly the extre- 

 mity of one of them, and, placing it be- 

 fore the microscope, you may discover 

 the black spot at the end to be really a 

 semiglobular eye. 



The dissection of this animal is very cu- 

 rious ; for by this means, the microscope 

 not only discovers the heart beating, just 

 against the round hole near the neck, 

 which seems the place of respiration ; but 

 also the liver, spleen, stomach, and intes- 

 tines, with the veins, arteries, mouth, and 

 teeth, are plainly observable. The intes- 

 tines of this creature are green, from its 

 eating herbs, and are branched all over 

 with tine capillary white veins ; the mouth 

 is like a hare's or rabbit's, with four or six 

 needle-teeth, resemblingthose of leeches, 

 and of a substance like horn. Snails, are 

 all hermaphrodites, having both sexes 

 united in each individual ; they lay their 

 eggs with great care in the earth, and 

 the young ones are hatched with shells 

 completely formed. Cutting off a snail's 

 head, a little stone appears, which is-sup- 

 posed to be a great diuretic, and good in 

 nephritic disorders : immediately under 

 this stone, the heart is seen beating ; and 

 the auricles are evidently distinguishable, 

 and are membraneous, and of a white co- 

 lour, as are also the vessels which pro- 

 ceed from them. So small an animal as 

 the snail is not free from the plague of 

 supporting other smaller animals on its 

 body ; and, as in other animals, we find 

 these secondary ones either living on 

 their surface, as lice, &c. or only in the 

 Intestines as worms, it is very remarka- 

 ble, that the snail is infested in both these 

 manners, lice being sometimes found on 

 the surface of its body, and worms some- 

 times within its intestines. There is a 

 part of the common garden snail, and of 

 other of the like kinds, commonly called 

 the collar; this surrounds the neck of the 

 snail, and is considerably thick, and is the 

 only part that is visible when the animal 

 is retired quietly into its shell : in this 

 state of the animal, these insects which 

 infest it are usually seen in considerable 

 numbers, marching about very nimbly on 

 this part. 



HELLEBORUS, in botany, English hel- 

 lebore, a genus of the Polyandria Polygy- 

 nia class and order. Natural order of Mul- 

 tisiliquse. Ranunculacex, Jussieu. Essen- 

 tial character : calyx none ; petals five, or 

 more; nectary two-lippeL, tubular ; cap- 

 sules many-seeded. There are seven spe- 

 cies. The hellebores are all hardy her- 

 baceous perennials, with compound 



leaves, digitate, pedate, palmate, or ter- 

 nate ; the flowers have only a single co- 

 ver j they grow either several together, 

 at the ends of the stalk and its subdivisi- 

 ons, with a single bracte to each pedicle ; 

 or single on a scape, naked, or with a leaf 

 for an involucre. They appear early in. 

 the spring, and often in the winter. The 

 root of this plant is tuberous ; at first it has 

 no taste, but in a short time a strong 

 acridity becomes sensible to the mouth 

 and throat. By distillation, an oil is ob- 

 tained which is extremely poisonous: one 

 similar in its effects may be obtained from 

 many plants. 



HELM, in naval architecture, a long 

 and flat piece of timber, or an assemblage 

 of several pieces, suspended along the 

 hind part of a ship's stern-post, where it 

 turns upon hinges to the right or left, 

 serving to direct the course of the vessel, 

 as the tail of a fish guides the body. The 

 helm is usually composed of three parts, 

 viz. the rudder, the tiller, and tiie wheel, 

 except in small vessels, where the wheel 

 is unnecessary. As to the form of the rud- 

 der it becomes gradually broader in pro- 

 portion to its distance from the top, or to 

 its depth under the water. The back, or 

 inner part of it, which joins to the stern- 

 post, is diminished into the form of a 

 wedge throughout its whole length, so 

 as that the rudder may be more easily 

 turned from one side to the other, where 

 it makes an obtuse angle with the keel. 

 It is supported upon hinges, of which 

 those that are bolted round the stern- 

 post to the after extremity of the ship are 

 called googings, and are furnished with 

 a large hole in the after-part of the stern- 

 post. The other parts of the hinges, 

 which are bolted to the back of the rud- 

 der, are called pintles, being strong cy- 

 lindrical pins, which enter into the goog- 

 ings and rest upon them. The length and 

 thickness of the rudder is nearly equal 

 to that of the stern-post. The rudder 

 is turned upon its hinges by means of * 

 long bar of timber called the tiller, which 

 is -fixed horizontally in its upper end 

 within the vessel. The movements of 

 the tiller, to the right and left, according- 

 ingly direct the efforts of the rudder to 

 the government of the ship's course as 

 she advances; which, in the sealanguage, 

 is called steering. The operations of the 

 tiller are guided and assisted by a sort of 

 tackle, communicating with the ship's 

 side, called the tiller-rope, which is usu- 

 ally composed of untarred rope-yarns, for 

 the purpose <f traversing more readily 

 through the blocks or pulleys. In order 

 to facilitate the management of the helm, 



